Search

OBJECTIVE Diabetes is associated with high risk of cardiovascular (CV) events, particularly in patients with dyslipidemia and diabetic complications. We investigated the incidence of CV events with intensive or standard lipid-lowering therapy in patients with hypercholesterolemia, diabetic retinopathy, and no history of coronary artery disease (treat-to-target approach). RESEARCH DESIGN AND METHODS In this multicenter, prospective, randomized, open-label, blinded end point study, eligible patients were randomly assigned (1:1) to intensive statin therapy targeting LDL cholesterol (LDL-C) RESULTS Mean follow-up was 37 ± 13 months. LDL-C at 36 months was 76.5 ± 21.6 mg/dL in the intensive group and 104.1 ± 22.1 mg/dL in the standard group (P < 0.001). The primary end point events occurred in 129 intensive group patients and 153 standard group patients (hazard ratio [HR] 0.84 [95% CI 0.67–1.07]; P = 0.15). The relationship between the LDL-C difference in the two groups and the event reduction rate was consistent with primary prevention studies in patients with diabetes. Exploratory findings showed significantly fewer cerebral events in the intensive group (HR 0.52 [95% CI 0.31–0.88]; P = 0.01). Safety did not differ significantly between the two groups. CONCLUSIONS We found no significant decrease in CV events or CV-associated deaths with intensive therapy, possibly because our between-group difference of LDL-C was lower than expected (27.7 mg/dL at 36 months of treatment). The potential benefit of achieving LDL-C

OBJECTIVE To improve prognosis, it is important to predict the incidence of renal failure and cardiovascular disease in type 2 diabetic patients before the progression to advanced nephropathy. We investigated the predictive effects of urinary liver-type fatty acid–binding protein (L-FABP), which is associated with renal tubulointerstitial damage, in renal and cardiovascular prognosis. RESEARCH DESIGN AND METHODS Japanese type 2 diabetic patients (n = 618) with serum creatinine ≤1.0 mg/dL and without overt proteinuria were enrolled between 1996 and 2000 and followed up until 2011. Baseline urinary L-FABP was measured with an enzyme-linked immunosorbent assay. The primary end points were renal and cardiovascular composites (hemodialysis, myocardial infarction, angina pectoris, stroke, cerebral hemorrhage, and peripheral vascular disease). The secondary renal outcomes were the incidence of a 50% decline in estimated glomerular filtration rate (eGFR), progression to an eGFR RESULTS During a 12-year median follow-up, 103 primary end points occurred. The incidence rate of the primary end point increased in a stepwise manner with increases in urinary L-FABP. In Cox proportional hazards analysis, the adjusted hazard ratio in patients with the highest tertile of urinary L-FBAP was 1.93 (95% CI 1.13–3.29). This relationship was observed even when analyzed separately in normoalbuminuria and microalbuminuria. Patients with the highest tertile of urinary L-FABP also demonstrated a higher incidence of the secondary renal outcomes. CONCLUSIONS Our results indicate that urinary L-FABP may be a predictive marker for renal and cardiovascular prognosis in type 2 diabetic patients without advanced nephropathy.

Recent studies reveal a strong relationship between reduced mitochondrial content and insulin resistance in human skeletal muscle, although the underlying factors responsible for this association remain unknown. To address this question, we analyzed muscle biopsy samples from young, lean, insulin resistant (IR) offspring of parents with type 2 diabetes and control subjects by microarray analyses and found significant differences in expression of ∼512 probe pairs. We then screened these genes for their potential involvement in the regulation of mitochondrial biogenesis using RNA interference and found that mRNA and protein expression of lipoprotein lipase (LPL) in skeletal muscle was significantly decreased in the IR offspring and was associated with decreased mitochondrial density. Furthermore, we show that LPL knockdown in muscle cells decreased mitochondrial content by effectively decreasing fatty acid delivery and subsequent activation of peroxisome proliferator–activated receptor (PPAR)-δ. Taken together, these data suggest that decreased mitochondrial content in muscle of IR offspring may be due in part to reductions in LPL expression in skeletal muscle resulting in decreased PPAR-δ activation.

OBJECTIVE Individuals with type 2 diabetes are at high risk for cardiovascular events. We evaluated the prognostic value of gated myocardial perfusion single-photon computed tomography (SPECT) for asymptomatic diabetic patients in a Japanese population. RESEARCH DESIGN AND METHODS Asymptomatic patients (n = 485) aged ≥50 years with either a maximal carotid artery intima-media thickness of ≥1.1 mm, or a urinary albumin ≥30 mg/g creatinine or who had at least two of the following, abdominal obesity, low HDL cholesterol, high triglyceride levels, and hypertension, were enrolled at 50 institutions. The patients were evaluated using gated SPECT with the stress-rest protocol and followed up for 3 years. RESULTS During the follow-up period, 62 (13%) events occurred, including 5 cardiac deaths and 57 cardiovascular events. Patients with summed stress scores (SSS) of ≥9 had a significantly higher incidence (of either death or cardiovascular events) than those with SSS scores of CONCLUSIONS The incidences of cardiovascular events and death were significantly high in a select population of type 2 diabetic patients with SPECT abnormalities. A targeted treatment strategy is required for asymptomatic but potentially high-risk patients with type 2 diabetes.

OBJECTIVE Cross-sectional studies have reported increased levels of urinary type IV collagen in diabetic patients with progression of diabetic nephropathy. The aim of this study was to determine the role of urinary type IV collagen in predicting development and progression of early diabetic nephropathy and deterioration of renal function in a longitudinal study. RESEARCH DESIGN AND METHODS Japanese patients with type 2 diabetes (n = 254, 185 with normoalbuminuria and 69 with microalbuminuria) were enrolled in an observational follow-up study. The associations of urinary type IV collagen with progression of nephropathy and annual decline in estimated glomerular filtration rate (eGFR) were evaluated. RESULTS At baseline, urinary type IV collagen levels were higher in patients with microalbuminuria than in those with normoalbuminuria and correlated with urinary β2-microglobulin (β = 0.57, P < 0.001), diastolic blood pressure (β = 0.15, P < 0.01), eGFR (β = 0.15, P < 0.01), and urinary albumin excretion rate (β = 0.13, P = 0.01) as determined by multivariate regression analysis. In the follow-up study (median duration 8 years), urinary type IV collagen level at baseline was not associated with progression to a higher stage of diabetic nephropathy. However, the level of urinary type IV collagen inversely correlated with the annual decline in eGFR (γ = −0.34, P < 0.001). Multivariate regression analysis identified urinary type IV collagen, eGFR at baseline, and hypertension as factors associated with the annual decline in eGFR. CONCLUSIONS Our results indicate that high urinary excretion of type IV collagen is associated with deterioration of renal function in type 2 diabetic patients without overt proteinuria.

OBJECTIVE Genetic factors are believed to contribute to the development and progression of diabetic nephropathy. Recently, a genome-wide association study for diabetic nephropathy revealed four novel candidate loci in European American subjects with type 1 diabetes. In this study, we determined the association of the four loci with diabetic nephropathy in Japanese subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS We genotyped 11 singlenucleotide polymorphisms (SNPs) in four distinct loci (rs39059 and rs39075 in the CPVL/CHN2, rs1888747 and rs10868025 in FRMD3, rs739401 and rs451041 in CARS, and rs1041466, rs1411766, rs6492208, rs7989848, and rs9521445 in a chromosome 13q locus) in four independent Japanese populations. RESULTS Six SNPs were nominally associated with diabetic nephropathy in one of the four Japanese populations (P < 0.05; rs451041 in study 1; rs39059 and rs1888747 in study 3; rs1411766 in studies 1 and 4; and rs7989848 and rs9521445 in study 4); however, no significant association was observed for any SNP after correction for multiple testing errors in the individual populations. Nevertheless, a meta-analysis performed for the data obtained from all four populations revealed that one SNP (rs1411766) in chromosome 13q was significantly associated with diabetic nephropathy in the Japanese populations (nominal P = 0.004, corrected P = 0.04, odds ratio 1.26 [95% CI = 1.07–1.47]). CONCLUSIONS Our results suggest that the rs1411766 locus may be commonly involved in conferring susceptibility to diabetic nephropathy among subjects with type 1 or type 2 diabetes across different ethnic groups.

OBJECTIVE It is believed that disruption of vulnerable atherosclerotic plaque and subsequent thrombus formation play critical roles in the pathogenesis of cerebral infarction. We simultaneously determined four relatively common genetic variants related to plaque rupture or subsequent local thrombus formation and evaluated the combined effect on cerebral infarction. RESEARCH DESIGN AND METHODS We enrolled 3,094 Japanese type 2 diabetic subjects (62.7% male; aged 61.5 ± 8.4 years) and determined their genotypes regarding matrix metalloproteinase 9 C-1562T, coagulation factor XII (F12) C46T, von Willebrand factor (VWF) G-1051A, and plasminogen activator inhibitor (PAI-1) 675 4G/5G polymorphisms. The diagnosis of cerebral infarction was performed based on history, physical examination, and neuroimaging. RESULTS The single association analysis revealed that there were no statistically significant associations between each polymorphism and the prevalence of cerebral infarction. Interestingly, the prevalence of cerebral infarction was higher with the increase of the total number of four concomitant unfavorable proatherothrombotic alleles in each subject (P value for linear trend = 0.004). Furthermore, a multiple logistic regression analysis showed that the number of proatherothrombotic alleles was a risk factor for cerebral infarction independently of conventional risk factors (odds ratio for one-point increase in the number of proatherothrombotic allele 1.15 [95% CI 1.05–1.26], P = 0.004). CONCLUSIONS Accumulation of gene polymorphisms related to plaque rupture and thrombus formation is likely associated with the prevalence of cerebral infarction in type 2 diabetic patients, suggesting that the combined information about these variants is useful to assess the risk of cerebral infarction.

OBJECTIVE Albuminuria in type 2 diabetic patients is a risk factor for cardiovascular disease. We investigated the correlation between albuminuria and spontaneous microaggregation of platelets (SMAP) formed under shear stress. RESEARCH DESIGN AND METHODS The study subjects were 401 type 2 diabetic individuals (252 with normoalbuminuria and 149 with albuminuria) who were examined for SMAP under conditions of shear stress only (no agonist stimulation) and the reversibility of platelet microaggregation after stimulation with 1 μmol/l ADP, measured by a laser light-cattering method. Active glycoprotein IIb/IIIa (GPIIb/IIIa) and P-selectin expression levels on platelets as an index of platelet activation were measured by whole-blood flow cytometry. RESULTS SMAP formation was noted in 53% of diabetic patients. All patients with SMAP showed an irreversible pattern of platelet microaggregates by a low dose of ADP. SMAP was observed in 75% of diabetic subjects with albuminuria and in 39% of those with normoalbuminuria. Multivariate logistic regression analysis identified urinary albumin excretion rate and brachial-ankle pulse-wave velocity as independent factors associated with SMAP. The degree of SMAP correlated with active GPIIb/IIIa (γ = 0.59, P < 0.001) and P-selectin (γ = 0.55, P < 0.001) expression levels. These early-activated platelet profiles were significantly inhibited in albuminuric patients with aspirin intake, although the effect was incomplete. CONCLUSIONS Our study demonstrated an independent association between albuminuria and early changes in activated platelet profiles of type 2 diabetic patients. Further follow-up and intervention studies are needed to establish whether the inhibition of SMAP affects the course of cardiovascular disease in type 2 diabetic patients.

OBJECTIVE—Recently, several genes have been shown to be associated with an increased risk of type 2 diabetes by genome-wide association studies in white populations. To further investigate the involvement of these polymorphisms in conferring susceptibility to type 2 diabetes, we examined the association of 14 single nucleotide polymorphisms (SNPs) within 11 candidate loci with type 2 diabetes in a Japanese population.RESEARCH DESIGN AND METHODS—We analyzed 14 SNPs (rs4402960 in IGF2BP2, rs10811661 in CDKN2A/B, rs1111875 and rs7923837 in HHEX, rs13266634 in SLC30A8, rs1113132 and rs11037909 in EXT2, rs9939609 and rs8050136 in FTO, rs7756992 in CDKAL1, rs1801282 in PPARG Pro12Ara, rs5219 in KCNJ11 Glu23Lys, rs7480010 in LOC387761, and rs9300039 in Ch11) in 1,630 Japanese subjects with type 2 diabetes and in 1,064 control subjects by using an invader assay or a TaqMan assay.RESULTS—Among the 11 loci examined, 6 were significantly associated with type 2 diabetes in our population by a logistic regression analysis, similar to previously reported results (rs4402960, P = 0.00009; rs10811661, P = 0.0024; rs5219, P = 0.0034; rs1111875, P = 0.0064; rs13266634, P = 0.0073; rs7756992, P = 0.0363). In this population, the remaining five loci were not significantly associated with type 2 diabetes. In addition, we identified significant association of the SNPs in FTO gene with BMI in the control subjects.CONCLUSIONS—We have identified 6 of the 11 loci that were identified by genome-wide association studies in white populations, and these loci are considered strong candidates for type 2 diabetes susceptibility across different ethnicities.

OBJECTIVE—Metabolic syndrome is diagnosed according to several criteria. Of these, some require glucose intolerance and others require obesity for the diagnosis. We investigated the relationship between metabolic risk factor clustering and cardiovascular disease (CVD) mortality stratified by high blood glucose or obesity. RESEARCH DESIGN AND METHODS—We followed 7,219 Japanese men and women without a history of CVD for 9.6 years. We defined high blood pressure, high blood glucose, high triglycerides, low HDL cholesterol, and obesity as metabolic factors. The multivariate adjusted hazard ratio (HR) for CVD mortality according to the number of clustering metabolic factors was calculated using the Cox proportional hazards model. RESULTS—During follow-up, 173 participants died of CVD. The numbers of metabolic risk factors and CVD mortality were positively correlated (Ptrend = 0.07). The HR was obviously higher among participants with than among those without high blood glucose and clustering of ≥2 other metabolic risk factors (HR 3.67 [95% CI 1.49–9.03]). However, the risk increase was only modest in participants without high blood glucose even if they had ≥2 other metabolic risk factors (1.99 [0.93–4.28]). Conversely, metabolic risk factor clustering was related to CVD mortality irrespective of obesity. CONCLUSIONS—Our findings suggest that glucose tolerance plays an important role in CVD mortality. Because the prevalence of nonobese participants with several metabolic risk factors was quite high and their CVD risk was high, excluding them from the diagnosis of metabolic syndrome because of the absence of obesity might overlook their risk.

To estimate the frequency of remission/regression of microalbuminuria and to identify factors affecting such outcomes in Japanese patients with type 2 diabetes, we observed 216 patients with type 2 diabetes and microalbuminuria enrolled during an initial 2-year evaluation period for the next 6 years. Remission was defined as shift to normoalbuminuria and regression as a 50% reduction in urinary albumin excretion rate (AER) from one 2-year period to the next. Reduction of urinary AER was frequent, with a 6-year cumulative incidence of 51% (95% CI 42–60) for remission and 54% (45–63) for regression, whereas the frequency of progression to overt proteinuria was 28% (19–37). Microalbuminuria of short duration, the use of renin-angiotensin system-blocking drugs, and lower tertiles for HbA1c (

OBJECTIVE—To clarify whether stiffness and impaired blood flow in lower-leg arteries are associated with severity of coronary artery calcification among asymptomatic diabetic patients. RESEARCH DESIGN AND METHODS—We enrolled 102 asymptomatic type 2 diabetic patients with no history of cardiovascular complications consecutively admitted to our hospital. Agatston coronary artery calcium (CAC) score, as a marker of coronary artery calcification, was obtained using electron-beam computed tomography. Total flow volume and resistive index, as an index of vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial-ankle pulse-wave velocity (PWV), as an index of distensibility in the lower-extremity arteries, was also measured using an automatic device. RESULTS—When the patients were grouped according to CAC scores of 0–10 (n = 54), 11–100 (n = 25), and >100 (n = 23), those with the highest scores, which is considered to show possible coronary artery disease, showed the highest brachial-ankle PWV (P < 0.001) and resistive index (P < 0.001) and the lowest total flow volume (P < 0.001) among the groups. Simple linear regression analyses showed that both brachial-ankle PWV (r = 0.508, P < 0.001) and resistive index (r = 0.500, P < 0.001) were positively correlated and total flow volume (r = −0.528, P < 0.001) was negatively correlated with the log-transformed CAC score. Receiver operator characteristic curve analyses indicated that 1,800 cm/s for brachial-ankle PWV, 1.03 for resistive index, and 70 ml/min for total flow volume were diagnostic values for identifying patients with the highest scores. CONCLUSIONS—Quantitatively assessed stiffness and impaired blood flow in lower-leg arteries may help identify diabetic patients with possible coronary artery disease.

Streptozocin (STZ)-induced diabetic rats show hyperalgesia that is partially attributed to altered protein kinase C (PKC) activity. Both attenuated neuronal nitric oxide synthase (nNOS)-cGMP system and tetrodotoxin-resistant (TTX-R) Na channels in dorsal root ganglion neurons may be involved in diabetic hyperalgesia. We examined whether PKCβ inhibition ameliorates diabetic hyperalgesia and, if so, whether the effect is obtained through action on neurons by testing nociceptive threshold in normal and STZ-induced diabetic rats treated with or without PKCβ-selective inhibitor LY333531 (LY) and by assessing the implication of LY in either nNOS-cGMP system or TTX-R Na channels of isolated dorsal root ganglion neurons. The decreased nociceptive threshold in diabetic rats was improved either after 4 weeks of LY treatment or with a single intradermal injection into the footpads. The treatment of LY for 6 weeks significantly decreased p-PKCβ and ameliorated a decrease in cGMP content in dorsal root ganglia of diabetic rats. The latter effect was confirmed in ex vivo condition. The treatment with NO donor for 4 weeks also normalized both diabetic hyperalgesia and decreased cGMP content in dorsal root ganglions. The expressions of nNOS and TTX-R Na channels were not changed with LY treatment. These results suggest that LY is effective for treating diabetic hyperalgesia through ameliorating the decrease in the nNOS-cGMP system.

A newly identified 3'-untranslated region (UTR) polymorphism of the gene for skeletal muscle-specific glycogen-targeting subunit of protein phosphatase 1 (PPP1R3) was associated with insulin resistance and type 2 diabetes in Pima Indians (Xia J, Scherers W, Cohen PTW, Majer M, Xi T, Norman RA, Knowler WC, Bogardus C, Prochazka M: A common variant in PP1R3 associated with insulin resistance and type 2 diabetes. Diabetes 47:1519-1524, 1998). Thus, we investigated the frequency of polymorphism of the adenine- and thymine-rich element (ARE-1 and its variant ARE-2) in 426 Japanese type 2 diabetic and 380 nondiabetic subjects using a polymerase chain reaction (PCR)-restriction enzyme fragment length polymorphism (RFLP) method. The allele frequency of the ARE-2 variant in diabetic subjects was higher than that in nondiabetic subjects (0.34 vs. 0.29; P < 0.05), even though its frequency in Japanese subjects was lower (P < 0.001) than the reported value in Pima Indians (0.56). An aspartate polymorphism at codon 905 was 100% coupled to the ARE-2 allele, and its allele frequency was higher also in diabetic subjects. Although a serine substitution at codon 883 was partially linked with the ARE-2 allele, there was no difference between diabetic and nondiabetic subjects. These results indicate that the frequency of polymorphism of the PPP1R3 gene (ARE-2 and Asp905) is different between two ethnic groups and is increased in Japanese people with type 2 diabetes, suggesting that these variants may be a possible marker for searching for diabetogenic genes.

Reduction of microalbuminuria in patients with type 2 diabetes mellitus: the Shiga Microalbuminuria Reduction Trial (SMART) Received for publication 8 December 2006 and accepted in revised form 2 March 2007. Takashi Uzu, Makoto Sawaguchi, Hiroshi Maegawa, Atsunori Kashiwagi, for the Shiga Microalbuminuria Reduction Trial (SMART) group*

In our previous study (Diabetes 44:520–526, 1995), endothelial cells cultured in high glucose condition showed impairment of an oxidant-induced activation of the pentose phosphate pathway (PPP) and a reduced supply of NADPH to the glutathione redox cycle. To gain insight into the mechanisms of this impairment, the protective effect of pyruvate was studied in human umbilical vein endothelial cells cultured in either 5.5 mmol/l glucose (normal glucose [NG] condition) or 33 mmol/l glucose (high glucose [HG] condition). Through pretreatment of cells with 0.2 mmol/l pyruvate for 5–7 days in the HG condition, glucose oxidation through the PPP and total cellular NADPH content in the presence of 0.2 mmol/l H2O2 were increased by 54 (P < 0.05) and 34%, respectively, and glutathione-dependent degradation of H2O2 in HG cells was enhanced by 41% (P < 0.01), when compared with those cells to which pyruvate was not added. The addition of pyruvate significantly reduced the fructose 1,6-bisphosphate (FDP) content and free cytoplasmic NADH/NAD ratio, estimated by increased pyruvate/lactate ratio in NG and HG cells exposed to H2O2. Furthermore, the addition of pyruvate also showed a 46% reduction (P < 0.01) of endothelial cell damage induced by H2O2 in HG cells. These results indicate that abnormalities in PPP activation and glutathione redox cycle activity induced by H2O2 in HG cells are compensated, and that the accentuated reductive stress is improved by an addition of pyruvate. These pyruvate effects are associated with protection against an oxidant-induced endothelial cell injury in the high glucose condition.

The effects of glucose concentration on D-glucose oxidation and reduced nicotinamide adenine dinucleotide phosphate (NADPH) supply were studied during exposure of cultured human umbilical vein endothelial cells to hydrogen peroxide (H2O2). The activation of glucose oxidation via the pentose phosphate pathway (PPP), induced by exposure of cells to 200 μmol/l H2O2 for 1 h, was reduced by 50% (P < 0.01) in cells cultured for 5–7 days in 33 mmol/l D-glucose (HG) versus those cultured in 5.5 mmol/l D-glucose without (NG) or with (HR) 27.5 mmol/l D-raffinose. The intracellular NADPH content in HG cells, but not in NG or HR cells, was decreased by 42% (P < 0.01) by exposing cells to 200 μmol/l H2O2. The decrease in NADPH was dependent on D-glucose concentration in the medium and was prevented in glutathione (GSH)-depleted cells. The latter observation suggests that the decrease in NADPH is associated with activation of the GSH redox cycle. In the presence of 200 μmol/l H2O2, lactate release into the medium, NADH/NAD ratio, and phosphofructokinase activity in HG cells were 56, 53, and 68% greater, respectively, than in the NG group, which indicates that inhibition of glycolysis by H2O2 is less marked in the HG group compared with NG group. These results indicate that activation of the PPP was impaired in endothelial cells cultured under conditions of high-glucose and oxidative stress, resulting in a decreased supply of NADPH to various NADPH-dependent pathways, including the GSH redox cycle.

Prevention of cardiovascular disease is an important therapeutic goal in patients with type 2 diabetes mellitus (1). Although a low dose of aspirin is recommended for this purpose, some patients were resistant to aspirin (2). We previously reported that spontaneous microaggregation of platelets (SMAPs) formed under no stimulation with exogenous agonists were frequently observed in type 2 diabetic patients (3,4) and a considerable number of patients receiving aspirin still showed SMAP formation (4). The aim of the current study was to investigate whether a switch from aspirin to another antiplatelet drug could improve an insufficient platelet response to aspirin in diabetic patients. This was an open-label, single-arm, uncontrolled trial of antiplatelet treatment with 200 mg cilostazol daily (a phosphodiesterase III inhibitor) as an alternative to aspirin in 24 Japanese type 2 diabetic patients who persistently showed the inadequate SMAP formation despite treatment with …

It is well-known that oxidative stress plays critical roles in the pathogenesis of atherosclerotic diseases. In this study, we examined the association between four common genetic variants related to oxidative stress (glutamate-cysteine ligase modifier subunit (GCLM) C-588T, myeloperoxidase G-463A, human paraoxonase-1 Gln192Arg, and NADPH oxidase p22phox C242T) and the prevalence of myocardial infarction in type 2 diabetic patients. All type 2 diabetic patients who periodically attended the outpatient diabetes clinics of five participating hospitals were asked to participate in this study. Subjects who were eligible had type 2 diabetes, diagnosed by diabetologists based on World Health Organization criteria, and were aged ≥50 years. A total of 2,561 type 2 diabetic subjects were included: men, 62%; age, mean ± SD 60.9 …

The number of β-adrenergic receptors in cardiac myocytes isolated from rats made diabetic with streptozocin (STZ) for 10 wk was measured by use of a hydrophilic nonselective antagonist [3H]CGP 12177 and was found to decrease to 59% of the number in control rats (P < .05), without any change in affinity. Similarly, using [125I]iodocyanopindolol as a ligand, we found a decrease in the β-adrenergic-receptor number on cardiac plasma membrane isolated from the diabetic rats [29% decrease (P < .05) at 1 wk, 50% (P < .01) at 3 wk, and 49% (P < .01) at 10 wk compared with control rats]. However, the serum triiodothyronine level that had been known to modulate the β-adrenergic-receptor-adenylate cyclase system was decreased in the 1-wk-diabetic rats but not in the 10-wk-diabetic rats compared with each control group. Furthermore, there was no difference in urinary catecholamine excretion between diabetic and control groups. In the 10-wk-diabetic rats, the response of adenylate cyclase to isoproterenol was significantly defective (56% decrease compared with control rats; P < .05), although both the basal and the forskolin-stimulated maximum adenylate cyclase activities and a half-maximum concentration of isoproterenol for the stimulation of adenylate cyclase were similar in control and diabetic rats. On the other hand, both cholera toxin-dependent and islet-activating protein-dependent [32P]NAD incorporations into cardiac plasma membrane were markedly increased in the diabetic rats. The 2-wk insulin treatment improved not only the number of β-adrenergic receptors but also the response of adenylate cyclase to 10 μM isoproterenol. These results indicate that cardiac unresponsiveness to a β-adrenergic agonist in STZ-induced diabetic rats is specifically associated with a deficiency in the β-adrenergic-receptor concentration in cardiac plasma membrane.

A rapid paper-strip test for the semiquantitating 3-hydroxybutyrate (3-OHBA) has been developed. The color develops within 5 min after applying the serum to the paper strip, and the purple color was read either visually or by reflectance meter. This can detect 3-OHBA levels as low as 0.1 mmol/L up to 2.0 mmol/L. The more concentrated sample can be measured on serial dilution. Clinical usefulness has been tested in a summer camp for insulin-dependent diabetic children as well as in a routine diabetes clinic. Serum 3-OHBA levels ranged from > 100 µumol/L to 4 mmol/L in all the subjects before breakfast in a summer camp. In four subjects, 3-OHBA was elevated to the level of 2–4 mmol/L, and only one of these four subjects exhibited ketonuria by nitroprusside test. In a diabetes clinic, a new paper-strip test for 3-OHBA has revealed ketonemia in 34 (74%) of 46 diabetic subjects, while nitro-prusside test revealed ketonemia in only 4 (13%). The present paper-strip test for 3-OHBA is sensitive enough to detect levels as low as 0.1 mmol/L and is clinically useful for rapid detection of ketosis proneness as well as for monitoring of diabetes control.