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Apolipoprotein M (apoM), primarily carried by HDL, has been associated with several conditions, including cardiovascular disease and diabetic nephropathy. This study proposes to examine whether plasma apoM levels are associated with the development of diabetic kidney disease, assessed as progression to macroalbuminuria (MA) and chronic kidney disease (CKD). Plasma apoM was measured using an enzyme immunoassay in 386 subjects from the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) cohort at DCCT entry and closeout and the concentrations used to determine the association with risk of progression to kidney dysfunction from the time of measurement through 18 years of EDIC follow-up. apoM levels, at DCCT baseline, were higher in patients who developed CKD than in those who retained normal renal function. At DCCT closeout, participants who progressed to MA, CKD, or both MA and CKD also had significantly higher apoM levels than those who remained normal, and increased levels of apoM were associated with increased risk of progression to both MA (risk ratio [RR] 1.30 [95% CI 1.01, 1.66]) and CKD (RR 1.69 [95% CI 1.18, 2.44]). Our results strongly suggest that alterations in apoM and therefore in the composition and function of HDL in type 1 diabetes are present early in the disease process and are associated with the development of nephropathy.

We determined the relationship between plasma kallikrein and cardiovascular disease (CVD) outcomes as well as major adverse cardiovascular events (MACE) in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) cohort of type 1 diabetes (T1D). Plasma kallikrein levels were measured longitudinally in 693 subjects at DCCT baseline (1983–1989), midpoint (1988–1991), and end (1993) and at EDIC years 4–6 (1997–1999), 8–10 (2001–2003), and 11–13 (2004–2006). Cox proportional hazards regression models assessed the association between plasma kallikrein levels and the risk of CVD. In unadjusted models, higher plasma kallikrein levels were associated with higher risk of any CVD during DCCT/EDIC (hazard ratio [HR] = 1.16 per 20 nmol/L higher levels of plasma kallikrein; P = 0.0177) as well as over the EDIC-only period (HR = 1.22; P = 0.0024). The association between plasma kallikrein levels and the risk of any CVD remained significant during the EDIC follow-up after adjustment for age and mean HbA1c (HR = 1.20; P = 0.0082) and in the fully adjusted model for other CVD risk factors (HR = 1.17; P = 0.0330). For MACE, higher plasma kallikrein levels were associated with higher risk in the unadjusted (HR = 1.25; P = 0.0145), minimally adjusted (HR = 1.23; P = 0.0417, and fully adjusted (HR = 1.27; P = 0.0328) models for EDIC only. These novel findings indicate that plasma kallikrein level associates with the risk of any CVD and MACE in T1D individuals.

Low-income African Americans (AA) and Whites with extreme duration of young-onset diabetes (YODM) are a unique population. Traits of this population surviving w/DM for 50 yrs can provide clues to longevity in YODM, particularly in the poor and underserved. Persons ≥50 yrs old (59% female, 60% AA) from the Southern Community Cohort Study diagnosed w/DM < age 30 (n=649), classified by DM duration ≥ 50 yrs (extreme duration, n=96) or Disclosure E. Campos: None. H.A. Keenan: None. M.F. Lopes-Virella: None. W.J. Blot: None. B. Conway: None. Funding 5U01CA202979-04

GPR40 is a G-protein coupled receptor for medium and long-chain fatty acids. Since GPR40 is highly expressed in pancreatic islets and GPR40 activation increases glucose-stimulated insulin secretion from pancreatic beta cells, GPR40 is considered as a potential target for treatment of type 2 diabetes mellitus (T2DM). However, although nonalcoholic fatty liver disease (NAFLD) is a common complication of T2DM and GPR40 is also expressed in hepatocytes and macrophages, the role of GPR40 in high-fat diet (HFD)-induced NAFLD in animal models remains unknown. In this study, we fed wild type or GPR40 knockout (KO) C57BL/6 mice low-fat diet (LFD) or HFD for 20 weeks and then analyzed the effect of GPR40 KO on HFD-induced NAFLD. Metabolic assays showed that HFD increased bodyweight, glucose, insulin, insulin resistance, cholesterol and alanine aminotransferase (ALT) as expected, but GPR40 KO did not further change these parameters in HFD-fed mice. Interestingly, in LFD-fed mice, GPR40 KO increased bodyweight, insulin, insulin resistance, cholesterol and ALT. Histological analysis and Oil Red O staining showed that HFD induced steatosis while GPR40 KO only slightly reduced HFD-induced steatosis. Surprisingly, GPR40 KO in LFD-fed mice induced steatosis. Furthermore, study showed that while HFD increased immunostaining of F4/80, a biomarker for macrophages, GPR40 KO also increased F4/80 immunostaining in LFD-fed mice. Finally, we found that while HFD increased mRNA expression of CD36, a scavenger receptor that also imports long-chain fatty acids into cells, by 5-fold in liver, GPR40 KO increased it by 9-fold in LFD-fed mice. Taken together, this study showed that GPR40 deficiency was associated with insulin resistance, dyslipidemia, steatosis and hepatic inflammation in LFD-fed mice. This study also showed that GPR40-deficiency led to a robust upregulation of CD36 expression in liver, which is likely involved in GPR40 deficiency-associated steatosis and hepatic inflammation. Disclosure Z. Lu: None. Y. Li: None. M.F. Lopes-Virella: None. Y. Huang: None. Funding National Institutes of Health (DE027070); U.S. Department of Veterans Affairs (BX000854)

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study demonstrated that intensive glucose control reduced the risk of developing diabetic peripheral neuropathy (DPN) and cardiovascular autonomic neuropathy (CAN). We evaluated multiple risk factors and phenotypes associated with DPN and CAN in this large, well-characterized cohort of participants with type 1 diabetes, followed for >23 years. DPN was defined by symptoms, signs, and nerve conduction study abnormalities in ≥2 nerves; CAN was assessed using standardized cardiovascular reflex tests. Generalized estimating equation models assessed the association of DPN and CAN with individual risk factors measured repeatedly. During DCCT/EDIC, 33% of participants developed DPN and 44% CAN. Higher mean HbA1c was the most significant risk factor for DPN, followed by older age, longer duration, greater height, macroalbuminuria, higher mean pulse rate, β-blocker use, and sustained albuminuria. The most significant risk factor for CAN was older age, followed by higher mean HbA1c, sustained albuminuria, longer duration of type 1 diabetes, higher mean pulse rate, higher mean systolic blood pressure, β-blocker use, estimated glomerular filtration rate

Macrophage-mediated inflammation plays an essential role in diabetes-associated nonalcoholic steatohepatitis (NASH) and atherosclerosis. Our previous study has shown that acid sphingomyelinase (ASMase) plays a key role in the synergistic stimulation of inflammatory signaling by saturated fatty acid palmitate and lipopolysaccharide (LPS) in macrophages. In the current study, we assessed the effect of ASMase inhibition on NASH and atherosclerosis induced by lard-based, high palmitate-containing high-fat diet (HP-HFD) in combination with LPS in LDL receptor-knockout (LDLR-/-) mice. LDLR-/- mice were fed HP-HFD for 20 weeks and treated with or without a low dose of LPS and amitriptyline, an inhibitor of ASMase. Metabolic assays showed that amitriptyline reduced bodyweight, lipids and insulin resistance induced by HP-HFD or HP-HFD plus LPS. Histological study and Oil Red O staining of livers showed that while mice fed HP-HFD without LPS treatment had hepatic steatosis and hepatocellular ballooning, LPS further increased steatosis and ballooning by 70%. However, amitriptyline attenuated the effect of HP-HFD or HP-HFD plus LPS by 66%. Immunohistochemistry study showed that while mice fed HP-HFD without LPS treatment had a marked immunostaining of F4/80, a biomarker for macrophages, LPS further enhanced F4/80 immunostaining. However, amitriptyline significantly reduced F4/80 immunostaining. Furthermore, results showed that amitriptyline also attenuated atherosclerosis induced by HP-HFD plus LPS. To elucidate the underlying mechanisms, we found that amitriptyline downregulated proinflammatory cytokines by potently reducing sphingosine 1 phosphate, a bioactive sphingolipid. Taken together, this study showed that ASMase inhibition attenuated both NASH and atherogenesis induced by HP-HFD plus LPS and one of the mechanisms potentially involved in the attenuation is inhibition of S1P production. Disclosure Z. Lu: None. Y. Li: None. M.F. Lopes-Virella: None. Y. Huang: None. Funding U.S. Department of Veterans Affairs (1I01CX001825-01); National Institutes of Health

The risk for preeclampsia (PE) is increased 4-fold in women with type 1 diabetes (T1D), in whom we previously demonstrated that elevated cholesterol-rich lipoproteins confer risk at the 1st trimester. Sphingolipids, including ceramides (Cer) and glycosphingolipids (hexosyl- (HexCer) and lactosyl-ceramides (LacCer)), are lipoprotein constituents that regulate cell signaling. We propose that these bio-active lipids could be modulators of PE risk. In a prospective T1D pregnancy cohort (studied at 12, 22, 32 weeks’ gestation), we used liquid chromatography/electrospray ionization-tandem mass spectrometry to determine plasma levels of 12 species of Cer, HexCer, and LacCer in 23 women with T1DM who did vs. 24 who did not develop PE, and in 19 normotensive nondiabetic pregnant women. All were free of microalbuminuria and hypertension at enrolment; all visits preceded clinical PE onset. Results: Plasma levels of C22-Cer (1st and 3rd study visits); C26:1-Cer (1st and 2nd visits); C26-Cer (1st visit); C18-Cer and C18:1-Cer (2nd visit) were significantly higher in women with T1DM who did vs. did not develop PE. C22-Cer and C26-Cer were significantly lower in T1DM vs. non-T1DM (1st visit). There were no overall PE- or diabetes-related differences in any HexCer- or LacCer species. Longitudinally, most Cer and HexCer species increased throughout pregnancy in all groups (except C14- and C18-Cer; and C14 and C26-HexCer). C16-LacCer increased, while C22:1-, C26-, and C26:1-LacCer decreased as pregnancy advanced, independent of PE status. Independent of LDL-C, total Cer increased throughout pregnancy in all groups. Conclusions: Maternal Cer species may serve as early biomarkers for PE in women with T1DM. T1DM was associated with lower levels of two Cer species. Like cholesterol-rich lipoproteins, Cer, HexCer and some LacCer species increase as pregnancy advances in all groups, but other LacCer species decrease: the significance of these findings requires further study. Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. M.J. Leyva: None. J. Yu: None. A.J. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. A.J. Nankervis: None. K.F. Hanssen: None. S.K. Garg: Advisory Panel; Self; Eli Lilly and Company, Roche Pharma, Sanofi-Aventis, Zealand Pharma A/S. Research Support; Self; Eli Lilly and Company, WebMD. J.A. Scardo: None. C.E. Aston: None. T. Lyons: None. Funding JDRF; Novo Nordisk; National Institutes of Health

Preeclampsia (PE) occurs four times more frequently in pregnant women with type 1 diabetes (T1D) than in nondiabetic women. We hypothesized that elevated plasma advanced glycoxidation products (AGEs) predict PE in T1D women. In a prospective T1D pregnancy cohort (study visits at 12, 22, 32 weeks' gestation), we used liquid chromatography/mass spectrometry, with internal stable heavy isotope substituted standards, to determine plasma levels of nine AGE and oxidation products (carboxymethyl-lysine [CML], carboxyethyl-lysine [CEL], methylglyoxal-hydroimidazolone [MGHI], 3-deoxyglucosone hydroimidazolones [3DGH], methionine sulfoxide [MetSO], glyoxal hydroimidazolone [GHI], 3-nitrotyrosine [3NT], dityrosine [DT], 2-aminoadipic acid [2AAA]) in 23 women with T1DM who developed PE vs. 24 who did not, and in 19 nondiabetic normotensive pregnant women. These products have been associated with CVD and renal failure in non-pregnant cohorts. All women were free of microalbuminuria and hypertension at enrolment, and all visits preceded clinical PE onset. GFR was estimated (Chronic Kidney Disease Epidemiology Collaboration equation). Results: Plasma CML, CEL, MGHI, 3DGH, MetSO, GHI, and 2AAA did not differ between the three groups at any study visit, and thus did not predict preeclampsia in T1D. In T1D women who later developed PE, eGFR was inversely associated at V3 with CML (p=0.008), CEL (p=0.03), MGH1 (p=0.03), 3DGH (p=0.03), GHI (p Conclusions: Plasma AGEs did not predict PE in well-controlled, previously healthy T1D women, and levels did not differ from healthy nondiabetic controls. Uniquely, in T1D women who developed PE, plasma AGEs were associated with renal function, consistent with the notion that subclinical alterations in renal function precede PE. Disclosure H. Karanchi: None. C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. M.J. Leyva: None. J. Yu: None. A.J. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker’s Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. A.J. Nankervis: None. K.F. Hanssen: None. C.E. Aston: None. S. Howell: Employee; Self; PreventAGE Health Care, LLC. P.J. Beisswenger: Other Relationship; Self; PreventAGE Health Care, LLC. T. Lyons: None.

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study reported that intensive glucose control as assessed by hemoglobin A1c (HbA1c) reduced the risk of diabetic peripheral neuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) in type 1 diabetes (T1D), with long lasting benefits. We evaluated additional clinical parameters and risk factors that could contribute to the development of DPN and CAN in this cohort. DPN was assessed at three different times and defined as a composite of symptoms, signs, and abnormal nerve conduction studies in ≥2 nerves; CAN was assessed seven different times and defined based on R-R variation, Valsalva maneuver, and postural changes in blood pressure. Generalized estimating equation models were used to evaluate the association of DPN and CAN with individual risk factors over repeated time points spanning 30 years. Among 1,441 DCCT/EDIC participants, 32% developed DPN and 44% developed CAN. Higher mean HbA1c was the most significant risk factor for DPN (OR=1.56 per 1%, 95% CI 1.41,1.72). DPN was also associated with older age (1.43 per 5 years, 95% CI 1.31,1.55), longer duration of T1D, higher albuminuria, β-blocker use, higher mean diastolic blood pressure, and higher HbA1c at DCCT eligibility. CAN was associated (in order) with older age (1.51 per 5 years, 95% CI 1.40,1.63), longer duration of T1D (1.07 per 1 year, 95% CI 1.05,1.10), any sustained microalbuminuria (AER ≥30 mg/24 hour on two consecutive visits), higher mean HbA1c, higher mean and current pulse rate (likely as an indirect measure of CAN), higher mean systolic blood pressure, β-blocker use, any eGFR Disclosure B. Braffett: None. R. Gubitosi-Klug: None. J.W. Albers: Consultant; Self; Eli Lilly and Company. E.L. Feldman: None. C. Martin: None. N.H. White: None. T.J. Orchard: Consultant; Self; Boehringer Ingelheim International GmbH. M.F. Lopes-Virella: None. P. Raskin: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Gan & Lee Pharmaceuticals, Novo Nordisk A/S. R. Pop-Busui: Consultant; Self; Novo Nordisk A/S. Research Support; Self; AstraZeneca. Other Relationship; Self; American Diabetes Association. Funding Division of Diabetes Endocrinology & Metabolic Diseases (U01DK094176, U01DK094157); National Eye Institute; National Institute of Neurologic Disorders and Stroke; General Clinical Research Centers Program; Clinical Translational Science Center

Statin therapy reduces cardiovascular risk in type 2 diabetes (T2DM), partly by improving dyslipidemia, and partly through ‘pleiotropic’ effects. Sphingolipids, including ceramides, are amphiphilic components of lipoprotein surface monolayers. Sphingolipids regulate lipoprotein surface fluidity, and include key signaling molecules: ceramides are specifically associated with apoptosis and risk for premature coronary heart disease. Effects of statins on the sphingolipid content of lipoproteins are poorly defined. Using liquid chromatography/electrospray ionization-tandem mass spectrometry, we determined fasting plasma concentrations of individual ceramides (Cer), sphingomyelins (SM), and glycosphingolipids (hexosyl- and lactosyl-Cer) in plasma from 19 men and 21 women with T2DM, before and after treatment with rosuvastatin (10 mg/day, 6 weeks). Exclusion criteria were use of ‘statins’ in the preceding 6 months, and any current use of lipid-modifying agents. Using existing lipoprotein compositional data, we calculated effects of rosuvastatin therapy on non-HDL sphingolipid content. Results: Rosuvastatin reduced total cholesterol (C) (by 33%), triglycerides (20%), LDL-C (49%), and non-HDL particle number (34%); HDL-C was unaffected. It decreased total SM (15%), Cer (29%), and hexosyl- (30%) and lactosyl- (34%) Cer, independent of gender. Assuming HDL composition was unaffected, rosuvastatin reduced non-HDL SM by 42% and Cer by 61%: these reductions remained significant after correction for non-HDL-C and/or non-HDL lipoprotein surface area. Conclusions: In T2DM, rosuvastatin lowers not only the number of non-HDL particles, but also the sphingolipid, and especially the Cer, content of each particle. This effect is independent of gender, potentially anti-atherogenic, and may represent a new pleiotropic effect of statins. Further studies are needed to confirm these findings in isolated lipoprotein classes, and to determine mechanism(s). Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. A. Gosmanova: None. M.J. Leyva: None. C.E. Aston: None. T. Lyons: None.

We hypothesize in diabetes that augmented activity of the plasma kallikrein-kinin system reflect and contribute to vascular damage and inflammations. Our objective was to determine the role of plasma PK as a predictor of cardiovascular events in type 2 diabetes in the VADT cohort. Levels of plasma total prekallikrein (PK) were measured in 604 VADT patients, a median of 1.5 years after entry into the study. Participants were followed an average of 4.1 years. Hazard ratios (HRs) for CV endpoints in relation to PK tertiles and having a non-zero versus zero value for plasma active kallikrein (PAK) were calculated by Cox proportional hazard models. During follow-up, 4.9% had an MI and 7.4% had an MI or cardiovascular death. Because there was evidence that minority status modified the associations between PK and outcomes of interest, but there was very limited power in minorities, results are presented in the total population adjusting for minority status and limited to the non-Hispanic white (NHW) population (Table). After adjustments by conventional risk factors, in NHW individuals the hazard ratio comparing the middle to lowest tertile of PK levels was 3.94 (95% CI: 1.09, 14.2) for MI and 3.45 (95% CI: 1.25, 9.48) for MI combined with cardiovascular death. Our study indicates that plasma PK levels predict MI and cardiovascular death in NHW patients with type 2 diabetes. Disclosure K.J. Hunt: None. M.A. Jaffa: None. M. Sohn: None. M.F. Lopes-Virella: None. A.A. Jaffa: None. Funding National Heart, Lung, and Blood Institute

We have previously shown that high levels of oxidized LDL and AGE-LDL in circulating IC are strong predictors of atherosclerosis progression in 518 subjects with type 1 diabetes from the DCCT/EDIC cohort. In this study we investigated whether oxLDL, MDA-LDL and AGE-LDL in circulating IC measured in the same subjects at DCCT baseline were associated with acute CVD events. Three overlapping CVD outcomes were considered: any CVD events, major adverse cardiac and cerebrovascular events (MACE) and myocardial infarction (MI). Cox proportional hazards models assessed the association between IC biomarker values and the subsequent risk of CVD, using inverse probability weighting to obtain results representative of the full DCCT/EDIC cohort. Results: Levels of AGE-LDL, oxLDL and MDA-LDL in circulating IC, measured at baseline (Table) were significantly associated with the 3 CVD outcomes in unadjusted models and were minimally attenuated after adjustment for age and mean HbA1c. After adjustments for conventional CVD risk factors, including LDL-Chol, high levels of oxLDL-IC and MDA-LDL-IC remained independently associated with increased subsequent risk of any CVD, and higher oxLDL-IC with increased risk of MACE and MI events. Conclusions: High levels of oxLDL-IC measured more than one decade prior to the occurrence of CVD events identified patients at high risk, even after adjustment by LDL-C and conventional CVD risk factors. Disclosure M.F. Lopes-Virella: None. I. Bebu: None. K.J. Hunt: None. G. Virella: None. N.L. Baker: None. B. Braffett: None. J. Lachin: Board Member; Self; Tolerion, Inc. Funding National Institute of Diabetes and Digestive and Kidney Diseases

Preeclampsia (PE), a major cause of maternal and fetal morbidity and mortality worldwide, has significantly higher incidence in women with type 1 diabetes mellitus (T1DM) than in nondiabetic populations (∼20% vs. 5%, respectively). Sphingolipids are key signaling molecules, and have many roles in the structure and regulation of cellular functions. Sphingomyelin (SM) is the most abundant sphingolipid in plasma lipoproteins. There is evidence that altered SM metabolism may contribute to cardiovascular and renal complications in diabetes. We aimed to determine whether plasma concentrations of 12 SM species were associated with PE in T1DM in a prospective study of pregnancy of 23 T1DM women who developed PE and 24 T1DM who remained normotensive. Additionally, 19 normotensive nondiabetic pregnant women were included for reference. All subjects were free of microalbuminuria and hypertension at enrolment, and all visits (12, 22, 32 weeks’ gestation) preceded clinical PE onset. Results: There were no cross-sectional differences in total SM, or in any individual SM species, between diabetic women with and without PE, or between normotensive women with and without diabetes at any stage of gestation. With advancing gestation in all groups, C18-SM, C18:1-SM, C20-SM, C20:1-SM, C22-SM, C22:1-SM, C24-SM, and C24:1-SM increased (all p Conclusions: With advancing gestation, plasma concentrations of most SM species increased, as did LDL and VLDL; however, two long-chain and two very long-chain SM species decreased. Although there were no differences in SM according to diabetes or PE status at any time point, further studies should address the significance of differential changes of SM species during pregnancy. Disclosure C.B. Kelly: None. S.M. Hammad: None. R.L. Klein: None. M.F. Lopes-Virella: None. M.J. Leyva: None. J. Yu: None. A.J. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. A.J. Nankervis: None. K.F. Hanssen: None. S.K. Garg: Advisory Panel; Self; Eli Lilly and Company, Roche Pharma, Sanofi-Aventis, Zealand Pharma A/S. Research Support; Self; Eli Lilly and Company, WebMD. J.A. Scardo: None. C.E. Aston: None. T. Lyons: None. Funding JDRF; Novo Nordisk; National Institutes of Health

We investigated whether the composition of modified forms of LDL in circulating immune complexes (LDL-ICs) was associated with cardiovascular disease (CVD) outcomes, including any CVD, major adverse cardiac and cerebrovascular events (MACCE), myocardial infarction (MI), and coronary artery disease, in type 1 diabetes (T1D). Our results demonstrate that the baseline levels of oxidized LDL (oxLDL), MDA-modified LDL (MDA-LDL), and advanced glycosylation–modified LDL (AGE-LDL) in circulating ICs were associated with the four CVD outcomes in unadjusted models, and adjustment by age and mean HbA1c only resulted in minimal reduction of these associations. After adjustments were made for other cardiovascular risk factors, particularly LDL cholesterol, oxLDL-IC and MDA-LDL-IC remained independently associated with the risk of CVD, and oxLDL-IC was independently associated with the risk of MACCE and MI. In the majority of cases, the baseline levels of modified LDL-IC (measured many years before the occurrence of any CVD event) were associated with the risk of CVD over a 25-year period even after adjustment for other risk factors (including LDL cholesterol). Therefore, modified LDL biomarkers may help identify patients with T1D at high risk for MACCE and CVD events very early in the evolution of the disease, before other signals of disease are apparent.

Risk factors for cardiovascular disease (CVD) are well-established in type 2 but not type 1 diabetes (T1DM). We assessed risk factors in the long-term (mean 27 years) follow-up of the Diabetes Control and Complications Trial (DCCT) cohort with T1DM. Cox proportional hazards multivariate models assessed the association of traditional and novel risk factors, including HbA1c, with major atherosclerotic cardiovascular events (MACE) (fatal or nonfatal myocardial infarction [MI] or stroke) and any-CVD (MACE plus confirmed angina, silent MI, revascularization, or congestive heart failure). Age and mean HbA1c were strongly associated with any-CVD and with MACE. For each percentage point increase in mean HbA1c, the risk for any-CVD and for MACE increased by 31 and 42%, respectively. CVD and MACE were associated with seven other conventional factors, such as blood pressure, lipids, and lack of ACE inhibitor use, but not with sex. The areas under the receiver operating characteristics curves for the association of age and HbA1c, taken together with any-CVD and for MACE, were 0.70 and 0.77, respectively, and for the final models, including all significant risk factors, were 0.75 and 0.82. Although many conventional CVD risk factors apply in T1DM, hyperglycemia is an important risk factor second only to age.

The hypothesis that plasma prekallikrein (PK) is a risk factor for the development of vascular complications was assessed in a study using the Diabetes Control and Complications Trial (DCCT)/Epidemiology and Diabetes Interventions and Complications (EDIC) cohort of subjects with type 1 diabetes. The circulating levels of plasma PK activity were measured in the plasma of 636 subjects with type 1 diabetes (EDIC years 3–5). Common and internal carotid intima-media thickness (IMT) were measured by B-mode ultrasonography in EDIC years 1 and 6. Plasma PK levels were positively and significantly associated with BMI, hemoglobin A1c, systolic blood pressure, total cholesterol, LDL cholesterol, and triglycerides but not with age, sex, duration of diabetes, or HDL cholesterol. Univariate and multivariable statistical models after controlling for other risk factors consistently demonstrated a positive association between plasma PK and progression of internal carotid IMT. Multivariate analysis using a general linear model showed plasma PK to be significantly associated with progression of both internal and combined IMT (Wilks Λ P value of 0.005). In addition, the mean internal carotid IMT levels were higher in subjects with plasma PK levels in the highest 10th percentile compared with subjects with plasma PK levels in the lower 10th percentile (P = 0.048). These novel findings implicate plasma PK as a risk factor for vascular disease in type 1 diabetes.

Connective tissue growth factor (CTGF) is a member of the CCN family of matricellular proteins that has been implicated in the inflammatory process, response to injury and wound healing. An emerging role of CTGF is that of a profibrotic factor implicated in the development of kidney disease. Our objective was to determine the role of CTGF as a predictor of macroalbuminuria (ACR ≥300µg/mg twice) and chronic kidney disease (CKD) stage 3 (GFR Disclosure K.J. Hunt: None. M.A. Jaffa: None. S.M. Garrett: None. D.K. Luttrell: None. K.E. Lipson: Employee; Self; FibroGen, Inc.. Stock/Shareholder; Self; AbbVie Inc., Abbott, Becton, Dickinson and Company, Bristol-Myers Squibb Company, General Electric, Gilead Sciences, Inc., Medtronic, Nestlé, Novartis AG, Oracle, Pfizer Inc., Quest Diagnostics. Consultant; Spouse/Partner; Diabesen. M.F. Lopes-Virella: None. L.M. Luttrell: None. A.A. Jaffa: None.

There is considerable interest in identifying biomarkers indicative of plaque instability and acute events. Previously we reported that MDA-LDL in circulating immune complex predicted acute myocardial infarction (MI) in the VADT study. Interleukin (IL)-6, Fas Ligand, tissue inhibitor of MMP (TIMP)-1 and monocyte chemotactic protein (MCP)-1 have been identified as potentially clinically relevant biomarkers related to plaque instability. Therefore, our objective was to examine the role of these biomarkers in conjunction with MDA-LDL in circulating immune complex as predictors of acute MI in type 2 diabetes. Biomarker levels were measured in 833 VADT patients, a median of 2.0 years after study entry and participants were subsequently followed a median of 3.7 years. Biomarkers were examined individually and as composite scores created by summing z scores across biomarkers. Hazard ratios (HRs) for acute MI were calculated by Cox proportional hazard models. During follow-up, 5.2% had an MI. After adjustment for conventional risk factors, results of composite biomarkers scores were promising with a hazard ratio for acute MI of 4.65 (95% CI: 1.56, 13.9) comparing the fourth to first quartile of our summary composite score which included MDA-LDL-IC, IL-6, Fas Ligand,TIMP-1 and MCP-1 (Table). Disclosure M.F.L. Lopes-Virella: None. K.J. Hunt: None. R. Agarwal: None. N.L. Baker: Research Support; Self; Bristol-Myers Squibb Company. G. Virella: None.

Background: Serum uric acid (UA) is associated with the pathogenesis of diabetes complications, including cardiovascular disease (CVD) and kidney injury. Current epidemiological evidence is limited regarding the association between UA and the development of CVD in type 1 diabetes mellitus (T1DM). Objective: To examine associations of serum UA with CVD and major atherosclerotic cardiovascular events (MACE) in T1DM. Methods: UA was measured in sera (1997-2000) from a subset of participants (n=973; males=540, females=433) in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study. Subsequent CVD events were adjudicated by a review committee masked to DCCT assignment and HbA1c levels, and defined as the time to the first of any of the following: non-fatal myocardial infarction (MI) or stroke, CVD death, silent MI on annual ECG, angina confirmed by ischemic changes with exercise tolerance testing, congestive heart failure, or revascularization; MACE were defined as a composite of CVD death, nonfatal MI, or stroke. Cox proportional hazards models were used to evaluate prospectively the effect of UA as a fixed covariate on CVD and MACE, separately by gender, and adjusted for age and HbA1c. Results: Over 15 years follow-up, there were 201 adjudicated CVD events among 110 participants (HR=1.10 per 1 mg/dl change in UA, 95% CI 0.93-1.30); 61 males experienced 96 events (HR=1.15, 95% CI 0.90-1.46) and 49 females, 105 events (HR=1.17, 95% CI 0.88-1.56). There were 62 adjudicated MACE among 53 participants (HR=1.18, 95% CI 0.93-1.49); 29 males experienced 31 events (HR=1.10, 95% CI 0.77-1.58) and 24 females, 31 events (HR=1.47, 95% CI 1.01-2.14). No significant associations between quartiles of UA and either CVD or MACE were observed in either sex. Conclusions: Our results show UA may not serve as a predictive biomarker for CVD events in T1DM adults. Sex-specific associations with MACE deserve further investigation. Disclosure A. Basu: None. B. Braffett: None. A. Jenkins: Research Support; Self; Medtronic, Mylan, Sanofi-Aventis. I. Bebu: None. R.L. Klein: None. M.F. Lopes-Virella: None. S. Dagogo-Jack: None. T.J. Orchard: None. A. Wallia: Research Support; Self; UnitedHealth Group. Consultant; Self; Glytec Systems, Lexicon Pharmaceuticals, Inc.. Research Support; Self; Eli Lilly and Company. J. Lachin: Board Member; Self; AbbVie Inc., Celgene Corporation. W. Garvey: Advisory Panel; Self; Novo Nordisk Inc., Merck & Co., Inc.. Research Support; Self; Sanofi, Pfizer Inc., Novo Nordisk Inc., AstraZeneca, Merck & Co., Inc., Elcelyx Therapeutics, Inc., Lexicon Pharmaceuticals, Inc., Eisai Inc.. T. Lyons: None.

Background: Apolipoproteins Apo-B, Apo-C-III, and Apo-E are atherogenic and are associated with diabetic dyslipidemia and cardiovascular disease (CVD). Apolipoprotein-defined lipoprotein subclasses (ADLS) also show associations with CVD, but prospective associations of these detailed metrics with CVD in people with type 1 diabetes (T1DM) have not been explored. Objective: Prospective associations of serum apolipoproteins and ADLS with CVD and major atherosclerotic cardiovascular events (MACE: composite of CVD death, nonfatal myocardial infraction or nonfatal stroke) in T1DM. Methods: Serum apolipoproteins and ADLS (14 biomarkers in total) measured in sera (1997-2000) in a subset (n=465) of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications cohort. Prospective associations of CVD and MACE over 5942 and 6180 patient-years follow-up, respectively, were investigated using Cox proportional hazards models unadjusted and adjusted for risk factors. Results: During 15 years follow-up, 50 CVD and 24 MACE events occurred. Significant positive univariate associations for CVD were: Lp-B, Apo-B, Apo-C-III (total, heparin precipitate (HP), i.e., Apo-C-III in VLDL, and heparin soluble (HS), i.e., Apo-C-III in HDL) and Lp-B:C; for MACE: Apo-C-III sub fractions (total, Apo-C-III-HP, and Apo-C-III-HS). Adjusting for sex, age, HbA1c, systolic blood pressure, pulse rate, LDL-cholesterol, and triglycerides: for CVD, Apo-C-III-HS remained significant (HR (95% CI): 1.18 (1.03, 1.35); P=0.01). For MACE, total Apo-C-III and Apo-C-III-HS persisted when adjusted for age, HbA1c and LDL [1.11 (1.01, 1.22); P=0.02, and 1.22 (1.02, 1.45); P=0.02, respectively], but not for age, HbA1c and (log) triglycerides. No significant associations of other ADLS, Apo-A-I, A-II and Apo-E with CVD/MACE were observed. Conclusions: Total serum Apo-C-III and Apo-C-III in HDL and Apo-B-containing lipoproteins may serve as predictive biomarkers for CVD events in T1DM adults. Disclosure A. Basu: None. I. Bebu: None. A. Jenkins: Research Support; Self; Medtronic, Mylan, Sanofi-Aventis. J. Stoner: None. Y. Zhang: None. R.L. Klein: None. M.F. Lopes-Virella: None. W. Garvey: Advisory Panel; Self; Novo Nordisk Inc., Merck & Co., Inc.. Research Support; Self; Sanofi, Pfizer Inc., Novo Nordisk Inc., AstraZeneca, Merck & Co., Inc., Elcelyx Therapeutics, Inc., Lexicon Pharmaceuticals, Inc., Eisai Inc. M. Budoff: Speaker's Bureau; Self; Janssen Pharmaceuticals, Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Amarin Corporation. T. Lyons: None.

OBJECTIVE High cholesterol levels in circulating immune complexes (IC), surrogate markers of modified LDL, are associated with increased carotid intima-media thickness (IMT) and cardiovascular events in type 1 diabetes. Different modifications of LDL are involved in IC formation, but which of these are predictive of vascular events is not known. Therefore, we measured oxidized LDL (oxLDL), advanced glycation end products–modified LDL (AGE-LDL), and malondialdehyde-modified LDL (MDA-LDL) in IC and determined their relationship with increased carotid IMT and compared the strength of the association with that observed with conventional risk factors. RESEARCH DESIGN AND METHODS Levels of oxLDL, AGE-LDL, and MDA-LDL were measured in circulating IC isolated from sera of 479 patients of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort, collected at baseline. Internal and common carotid IMT were measured 8 and 14 years later by DCCT/EDIC. RESULTS OxLDL, AGE-LDL, and MDA-LDL levels in circulating IC were significantly correlated with diabetes duration, BMI, and lipid and blood pressure, but not with age. Multivariate logistic regression models indicated that individuals in the highest versus lowest quartile of oxLDL and AGE-LDL in IC had a 6.11-fold [confidence interval (CI) 2.51–14.8] and a 6.4-fold (CI 2.53–16.2) increase in the odds of having high carotid IMT, respectively, after adjusting for conventional risk factors. Parallel analyses resulted in odds ratios of 2.62 (CI 1.24, 5.55) for LDL-C, 1.45 (CI 0.69, 3.03) for diastolic blood pressure, and 2.33 (CI 1.09, 4.99) for A1C. CONCLUSIONS OxLDL and AGE-LDL in circulating IC were significantly associated with progression and increased levels of carotid IMT in type 1 diabetes.

The pathogenesis of excess cardiovascular risk in type 1 diabetes is unclear. LDL cholesterol is only weakly predictive, and its concentration is often normal in type 1 diabetes. We therefore examined whether markers of LDL oxidation such as antibodies to oxidized LDL (Ab-OxLDL) and LDL-containing immune complexes, rather than LDL concentration, were predictive of coronary artery disease (CAD) in type 1 diabetes. This nested case-control study from an epidemiologic cohort study included 49 incident cases of myocardial infarction (MI), angina, or CAD death and 49 age-, sex-, and duration-matched control subjects. Ab-OxLDL was measured by enzyme immunoassay and the apolipoprotein B (ApoB) content of immune complexes (ApoB-IC) precipitated by polyethylene glycol by immunoelectrophoresis in baseline stored samples. Ab-OxLDL was inversely, and ApoB-IC directly, related to subsequent CAD. In multivariate analyses, Ab-OxLDL remained a significant independent predictor along with previously recognized predictors, hypertension and Beck depression score. In conclusion, oxidation of LDL and the immune response it elicits may play a role in predicting the development of CAD in type 1 diabetes and explain at least some of the enhanced CAD risk in type I diabetes.

Modified lipoproteins, particularly different forms of oxidized LDL (ox-LDL), have been reported to elicit humoral immune responses both in experimental animals and humans. In diabetes, glycation and oxidation processes coexist and lead to the formation of glycoxidation products. Ox-LDL has been demonstrated in atheromatous lesions, anti-ox-LDL antibodies have been detected in circulation and in atheromatous plaques, and immune complexes (ICs) formed with LDL and anti-LDL (LDL-IC) have been isolated from the serum of patients with manifestations of atherosclerosis. In addition, in vitro formed LDL-ICs and ICs isolated from patients have been demonstrated to cause intracellular accumulation of cholesteryl esters (CEs) in human macrophages and fibroblasts. The accumulation of CEs in macrophages exposed to LDL-ICs is unique to this type of IC and is associated with paradoxical overexpression of LDL receptor and with increased synthesis and release of interleukin Iβ and tumor necrosis factor (TNF) α. The overexpression of LDL receptors is higher in LDL-IC-stimulated macrophages that release markedly high amounts of TNF-α than in macrophages that release low amounts of TNF-α into the medium. The release of cytokines in the subendothelial space may have a significant role in promoting the interaction of endothelial cells with mononuclear cells, causing endothelial cell damage directly or indirectly, and also in inducing smooth muscle cell proliferation. Thus, in view of the above data, it can be concluded that humoral autoimmunity may play a significant role in the pathogen-esis of atherosclerosis in diabetes.

The VLDL and LDL fractions were isolated from 29 patients with type 1 diabetes at the time of admission to the hospital to restore glycemic control and again at discharge. These lipoprotein fractions were incubated with human monocyte-derived macrophages, and the rates of macrophage CE synthesis were determined. The rates of CE synthesis in human macrophages were significantly greater (P < 0.005) when incubated with VLDL isolated from type I diabetic patients before compared with after glycemic control was attained and averaged 1.84 ± 0.52 and 1.09 ± 0.27 nmol (1.20 ± 0.34 and 0.71 ± 0.18 μg) [14C]cholesteryl oleate synthesized mg cell protein−1 · 20 h−1 respectively. In contrast, when LDL isolated from the same patient during the same period was incubated with human macrophages, the rates of cellular cholesteryl ester synthesis did not differ significantly and averaged 4.23 ± 1.26 and 3.91 ± 0.96 nmol (2.75 ± 0.82 and 2.55 ± 0.63 μg) [14C]cholesteryl oleate synthesized · mg−1 cell protein · 20 h−1, respectively. There was a significant increase in the total cholesterol content of VLDL isolated before glycemic control compared with that isolated after glycemic control was attained (P < 0.05) resulting from a significant increase in the FC and CE (P < 0.05) contents of these VLDL particles. There was a significant decrease in the ratio of FC to PL in VLDL, but not LDL, isolated after glycemic control (P < 0.05). The percentage of apoE in VLDL was significantly decreased (P < 0.05) after glycemic control was attained. In LDL isolated after glycemic control was achieved, a significant decrease (P < 0.005) in the percentage of triglycerides was observed. In addition, there was a significant decrease (P < 0.0001) in the extent of glycation of LDL isolated after glycemic control. These studies suggest that during periods of poor glycemic control, the composition of VLDL isolated from type 1 diabetic patients is altered. These modified VLDLs stimulate CE synthesis rates in human macrophages and, thus, may contribute to the increased prevalence of atherosclerosis in diabetic patients.

We investigated the hypothesis that modified lipoproteins trigger an immune response leading to the production of autoantibodies and subsequently to the formation of atherogenic immune complexes (IC). We recruited 20 type 2 diabetic patients with macrovascular disease, 14 nondiabetic patients with coronary artery disease (CAD), and 34 healthy control subjects matched for age, sex, and race. Serum antibodies to oxidized and glycated LDL did not differ significantly among the 3 groups. Serum IC contained variable, but not statistically different, amounts of IgG, IgM, and IgA. In contrast, the content of cholesterol in IC isolated from diabetic patients was significantly higher than that in IC isolated from control subjects, and the content of apolipoprotein (apo)-B was significantly higher than that in IC isolated from control subjects and patients with CAD. Cholesteryl ester accumulation in human monocyte-derived macrophages incubated with IC, a measure of the atherogenic potential of IC, was significantly higher in macrophages incubated with red blood cell-adsorbed IC isolated from diabetic patients compared with IC isolated from control subjects (P < 0.03) or from patients with CAD (P < 0.04) and was strongly correlated with the content of apoB (r = 0.68, P < 0.001) and cholesterol (r = 0.61, P < 0.001) in IC. LDL from diabetic patients was more susceptible to oxidation in vitro, was significantly smaller, and contained significantly less alpha-tocopherol than LDL isolated from subjects in the other groups. In addition, the n-3 polyunsaturated fatty acid content of phospholipids and cholesteryl esters in LDL isolated from diabetic patients was significantly increased (P < 0.05) compared with that from patients with CAD or from control subjects. We postulate that LDL size, susceptibility to oxidation, and lipid fatty acid composition may play a critical role in the production of antibodies to oxidized LDL and consequently in the formation of LDL-containing IC in patients with type 2 diabetes.

Increased susceptibility of LDL to oxidation has been shown to be associated with the presence of coronary heart disease and may account for the accelerated vascular disease seen in diabetes. The response of LDL to in vitro oxidative stress has been proposed as a measure of the predisposition of LDL to the in vivo subendothelial oxidative stress. Increased susceptibility to oxidation has been demonstrated recently in diabetic patients with poorly controlled IDDM. Thus, we conducted studies to determine whether the increased susceptibility of LDL to oxidation was secondary to diabetes per se or to the level of glycemic control. Fifteen IDDM patients with good glycemic control and with no evidence of macrovascular disease or proteinuria were compared with healthy age-, sex-, race-, and BMI-matched nondiabetic subjects. Fasting blood glucose levels averaged 12.1 +/- 1.1 (mean +/- SE) vs. 4.9 +/- 0.1 mmol/l in the diabetic versus the control groups, respectively. HbA1c levels averaged 7.7 +/- 0.5 vs. 4.4 +/- 0.2%, reflecting well-controlled diabetes (P < 0.0001). Total, LDL, VLDL, and HDL cholesterol, triglyceride, and lipoprotein(a) levels did not differ between the groups. The particle size, lipid composition, fatty acid content, antioxidant content, and glycation were similar for LDL isolated from both groups. A rapid LDL preparation technique was used to compare LDL susceptibility to oxidation under the following conditions: final LDL cholesterol concentration of 100 microg/ml, 5 micromol/l of CuCl2 at 25 degrees C. There was no difference in the susceptibility to in vitro oxidation of LDL isolated from IDDM patients compared with control subjects. There was no correlation of glycemic control with any of the parameters of the in vitro oxidation of LDL. LDL from patients with well-controlled IDDM does not differ in composition or in susceptibility to in vitro oxidative stress compared with LDL from nondiabetic subjects.

The total low-density lipoprotein (LDL) fraction was isolated from 21 patients with type I diabetes and 7 nondiabetic normolipemic subjects. The LDL was separated into two subfractions, one glycated (G-LDL) and one nonglycated (N-LDL), using affinity chromatography. G-LDL comprised 21.1 ± 3.6 and 5.2 ± 0.6% of the total LDL in diabetic patients and normal subjects, respectively. G-LDL isolated from both diabetic patients and normal subjects was significantly more glycated than N-LDL isolated from the same subject. G-LDL isolated from both diabetic patients and normal subjects was enriched in triglycerides. The metabolism of N-LDL and G-LDL was investigated in human fibroblasts, which express only the classical LDL receptor, and in human monocyte-derived macrophages, which also express a receptor for G-LDL. In fibroblasts, the rates of receptor-mediated accumulation of N-LDL isolated from normal subjects and diabetic patients were significantly greater (P < 0.01) than those of G-LDL. In contrast, when the same LDL subfractions were incubated with human monocyte-derived macrophages, the rates of receptor-mediatedaccumulation of G-LDL isolated from both groups were significantly greater (P < 0.01) than those of N-LDL. Rates of degradation of G-LDL by human macrophages were not significantly different from those of N-LDL during short-term incubations but reached statistical significance (P < 0.05) when LDL subfractions were incubated with cells for 24 h. G-LDL stimulated cholesteryl ester synthesis rates in human macrophages significantly (P < 0.05) more than N-LDL from the same subject and thus may contribute to the increased prevalence of atherosclerosis in diabetic patients.

It was recently proposed that the increased levels of modified lipoproteins in diabetic patients may be responsible for the accelerated development of macrovascular complications associated with the disease. Modified lipoproteins are believed to induce the transformation of macrophages into foam cells and, in some cases, to induce endothelial cell damage. In addition, modified lipoproteins trigger an immune response leading to the formation of antibodies and then to the formation of LDL-containing immune complexes. In this review, we summarize the evidence linking LDL glycation and oxidation with intracellular accumulation of cholesterol esters and foam-cell formation, and we discuss their potential for inducing an autoimmune response and the formation of lipoprotein-containing immune complexes. The formation of LDL-ICs seems particularly significant, because these ICs are avidly taken up by macrophages through their Fc receptors and induce not only massive intracellular accumulation of CE but also a paradoxical increase in LDL-receptor expression. Our experimental data suggest that the uptake of LDL-IC is facilitated by RBC adsorption, in agreement with the role of RBC in the adsorption of circulating IC and their delivery to phagocytic cells. In addition, macrophages are activated when ingesting LDL-IC and release IL-1β and TNF-α, which can contribute to the initiation and progression of an atheromatous lesion by several mechanisms. Although it is difficult to envisage how LDL-IC could initiate an endothelial lesion, it is easy to speculate about their role as cofactors in the initiation and progression of the atherosclerotic process.

Glucose can react with the lysine residues of low-density lipoproteins (LDLs) and convert the lipoprotein to a form with a receptor-mediated uptake by cultured cells that is impaired. However, in contrast to other modified lipoproteins taken up by both murine and human macrophages via the scavenger-receptor pathway that may induce the formation of foam cells, glycosylated LDL is not recognized by murine macrophages, and thus far, it has not been shown to lead to marked intracellular accumulation of cholesterol in human macrophages. This study illustrates that glycosylated LDL incubated with human monocyte-derived macrophages, at a concentration of 100 micrograms LDL/ml medium, stimulates significantly more cholesteryl ester (CE) synthesis than does control LDL (10.65 ± 1.5 vs. 4.8 ± 0.13 nmol.· mg−1 cell protein · 20 h−1; P < .05). At LDL concentrations similar to those of plasma, the rate of CE synthesis in macrophages incubated with glycosylated LDL is more markedly enhanced than that observed in cells incubated with control LDL (3-fold increase). The marked stimulation of CE synthesis in human macrophages exposed to glycosylated LDL is paralleled by a significant increase in CE accumulation in these cells (P < .001). The increase in CE synthesis and accumulation seem to be mediated by an increase in the degradation of glycosylated LDL by human macrophages. Glycosylated LDL enters the macrophages and is degraded by the classic LDL-receptor pathway in slightly smaller amounts than control LDL, but its degradation by pathways other than the classic LDL receptor or scavenger receptor is markedly enhanced. These studies have shown a possible mechanism by which glycosylation of LDL may lead to the formation of foam cells and contribute to the acceleration of atherosclerosis in diabetes mellitus.

Plasma lipid, lipoprotein, and apolipoprotein levels were measured in 55 insulin-dependent diabetics (20 males and 35 females) before and after 2–3 wk of intensive insulin therapy in a metabolic unit. At the time of discharge from the metabolic unit the levels of total, low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) cholesterol as well as triglycerides, VLDL triglycerides, and apolipoprotein B (Apo B) were significantly decreased. Conversely, the levels of high-density lipoprotein (HDL) cholesterol, and apolipoprotein A1 (Apo A1) were significantly increased. The data were further analyzed after subdividing the patients into two subgroups: (1) patients admitted in poor glycemic control (HbA1c > 11%) and (2) patients admitted in fair control (HbA1c < 11%). In the group admitted in poor control the changes in lipid and lipoprotein levels were similar to the ones found in the group of patients as a whole, while in patients admitted in fair control only the levels of total and VLDL triglycerides showed significant changes with control. Patients' sex appeared to influence the magnitude of changes observed in HDL cholesterol and Apo A1, levels. In males a significant increase in both HDL cholesterol and Apo A1 was achieved after glycemic control either in the whole group or in the subgroup admitted in poor control. In the subgroup admitted in fair control HDL cholesterol levels rose but no significant change was observed in the Apo A1 levels. In females no significant change was observed with improved control in HDL cholesterol and Apo A1, either in the whole group or in the group admitted in fair control. A small but significant increase was detected in the HDL cholesterol levels of the female patients admitted in poor control, but no change was observed in the Apo A1 levels. In conclusion, in insulin-dependent diabetics, normalization in plasma lipid, lipoprotein, and apolipoprotein levels was obtained after intensive insulin therapy.

Patients with diabetes mellitus manifest increased in vitro platelet aggregation andincreased synthesis of the proaggregant and vasoconstrictor, thromboxane A2 (TXA2). We studied the effects of continuous insulin infusion treatment on platelet aggregation and arachidonic acid (AA)-stimulated platelet TXA2 synthesis (15 and 30 s post-AA, 1 mM) in 16 type I diabetic patients. Strict glycemic control was induced with the Biostator for 2 days and maintained for 12–14 days with continuous subcutaneous insulin infusion (CSII). The average premeal plasma glucose level (4/day) fell from 184 ± 15, before treatment, to 107 ± 6 mg/dl on the final day (P < 0.001). After control, platelet synthesis of TXA2, measured by radioimmunoassay of its stable metabolite, immunoreactive TXB2 (iTXB2), decreased in all patients (30 s: 276 ± 31 versus 199 ± 28ng iTXB2/ml/ 5 × 105 platelets; P < 0.05). The reductionin platelet iTXB2 synthesis (15 and 30 s) was greater in poorly controlled patients (HbA1c>12%; N = 8), and for all patients the decrease in iTXB2 (15 and 30 s) was correlated with the prestudy HbA1c level (15 s: r = 0.6; P < 0.01). In contrast, platelet aggregation responses did not improve during intensive insulin treatment. The ED50 for AA (dose producing 50% maximum aggregation at 1 min) was unchanged after 2 wk of treatment and the ED50 for aggregation induced by ADP fell significantly inpatients with HbA1c 12% (2.8 ± 1.3 versus 1.2 ± 0.6 μM; P < 0.01). Other factors that were associated in this study with platelet aggregation responses were plasma lipoprotein levels and microvascular disease. In all patients before treatment, the ED50 for AA was inversely correlated with the LDL-cholesterol level(r = 0.57; P < 0.01). Although platelet aggregation did not improve during the period of intensive treatment, when the relations of microvascular disease and glycemic control to platelet aggregation were analyzed together in all patients, the ED50 for AA was greatest (P < 0.02) in thosepatients without microvascular disease and HbA1c Thus, a brief period of CSII treatment reduced AA-stimulated platelet iTXB2 generation; however, the effects of this treatment on platelet aggregation appear to be complex and other extraplatelet factors also seem to influence the aggregation response.

Low-density lipoprotein (LDL) is known to enhance platelet sensitivity to some aggregating agents. In this study, we observed that LDL isolated from patients with insulin-dependent diabetes mellitus (IDDM) enhanced thrombin-induced platelet aggregation to a greater extent than LDL isolated from matched controls (P < .01). Thromboxane B2 production during aggregation was also significantly more enhanced by LDL isolated from IDDM than by control LDL (P < .01). There was no difference in the lipid composition (free and esterified cholesterol, total phospholipids, and triglycerides) of LDL isolated from diabetic and control subjects. In contrast, the extent of glycosylation of LDL isolated from diabetic patients was significantly greater than that observed in LDL from normal subjects (P < .01), and a positive correlation (r = .605, P < .01) between the degree of LDL glycosylation and the rate of platelet aggregation was observed. LDL glycosylated in vitro enhanced thrombin-, collagen-, and adenosine 5'-diphosphate-induced platelet aggregation to a greater extent than control LDL (P < .01). Although LDL glycosylated in vitro was taken up by platelets to a greater extent than control LDL (P < .05), the lipid composition (free chojesterol and phospholipid) of platelets was not significantly changed. We postulate that an increased degree of glycosylation of LDL may enhance its uptake by platelets and lead to increased platelet reactivity to aggregating agents, probably by altering the structure of the platelet membrane. The enhancement of platelet aggregation by LDL may contribute to the accelerated development of atherosclerosis in diabetes mellitus.