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Blurred vision and cognitive difficulties are prominent symptoms during acute insulin-induced hypoglycemia. Our hypothesis was that changes in cerebral activity reflect these symptoms. Positron emission tomography (PET) with oxygen-15-labelled water was used to measure relative changes in regional cerebral blood flow (rCBF) as a marker of cerebral activity. Hypoglycemia was induced by intravenous insulin infusion in 19 healthy men performing two different cognitive tasks of varying complexity. The hypoglycemic stimulus [plasma glucose 2.2 mmol/liter (0.4)] produced a significant hormonal counterregulatory response. During the low cognitive load, rCBF decreased in response to hypoglycemia in a large bilateral area in the posterior part of the temporal lobe, and rCBF increased bilaterally in the anterior cingulate gyrus, the right frontal gyrus, the fusiform gyrus, thalamus, and the left inferior part of the frontal gyrus. During the high cognitive load, rCBF decreased bilaterally in a large region in the posterior part of the temporal gyrus and increased in the left and right anterior cingulate gyrus, left and right frontal gyrus, right parahippocampal and lingual gyrus, and left superior temporal gyrus. Visual impairment during hypoglycemia was associated with deactivation in the ventral visual stream. The anterior cingulate gyrus was activated during hypoglycemia in a load-dependent manner. Areas on the frontal convexity were differentially activated in response to the cognitive load during hypoglycemia. Our findings suggest that hypoglycemia induces changes in sensory processing in a cognition-independent manner, whereas activation of areas of higher order functions is influenced by cognitive load as well as hypoglycemia., ((c) 2009 Wiley-Liss, Inc.)

Background: Patients with type 2 diabetes (T2DM) have an increased mortality rate primarily because of macrovascular disease. Where T2DM patients cannot be managed sufficiently through diet, exercise and peroral antidiabetic drugs, that is when haemoglobin A1c (HbA1c) is above 7.0%, it is yet unknown whether a combination of metformin and insulin analogues is superior to insulin analogues alone. Nor is it known which insulin analogue regimen is the optimal., Objective: The primary objective of this trial is to evaluate the effect of an 18-month treatment with metformin vs. placebo in combination with one of three insulin analogue regimens, the primary outcome measure being carotid intima-media thickness (CIMT) in T2DM patients., Design: A randomized, stratified, multicentre trial having a 2 x 3 factorial design. The metformin part is double masked and placebo controlled. The insulin treatment is open. The intervention period is 18 months., Patient Population: Nine hundred and fifty patients with T2DM and HbA1c > or = 7.5% on treatment with oral hypoglycaemic agents or on insulin treatment and deemed able, by the investigator, to manage once-daily insulin therapy with a long-acting insulin analogue., Randomization: Central randomization stratified for age (above 65 years), previous insulin treatment and treatment centre., Interventions: Metformin 1 g x two times daily vs. placebo (approximately 475 patients vs. 475 patients) in combination with insulin detemir before bedtime (approximately 315 patients) or biphasic insulin aspart 30 before dinner with the possibility to increase to two or three injections daily (approximately 315 patients) or insulin aspart before the main meals (three times daily) and insulin detemir before bedtime (approximately 315 patients). Intervention follows a treat-to-target principle in all six arms aiming for an HbA1c < or = 7.0%., Outcome Measures: Primary outcome measure is the change in CIMT from baseline to 18 months. Secondary outcome measures comprises the composite outcome of death, acute myocardial infarction, stroke or amputation assessed by an adjudication committee blinded to intervention, other cardiovascular clinical outcomes, average postprandial glucose increment from 0 to 18 months, hypoglycaemia and any inadvertent medical episodes. In addition, change in plaque formation in the carotids, HbA1c, cardiovascular biomarkers, body composition, progression of microvascular complications and quality of life will be assessed as tertiary outcome measures. TIME SCHEDULE: Patient enrolment started May 2008. Follow-up is expected to finish in March 2011., Conclusion: CIMT is designed to provide evidence as to whether metformin is advantageous even during insulin treatment and to provide evidence regarding which insulin analogue regimen is most advantageous with regard to cardiovascular disease.

Aims: To investigate whether increased risk of severe hypoglycaemia in early pregnancy is related to pregnancy-induced changes in renin-angiotensin system (RAS) activity in women with type 1 diabetes (T1DM)., Methods: Severe hypoglycaemic events the year preceding pregnancy were recorded retrospectively in 107 consecutive pregnant women with T1DM. Events during pregnancy were recorded prospectively. Measurements of ACE, renin and angiotensinogen were determined at 8, 14, 21, 27 and 33 weeks and postpartum., Results: The rate of severe hypoglycaemia was 1.1 and 5.3 events/patient-year the year preceding pregnancy and in first trimester, respectively (p<0.0001). Levels of ACE, renin or angiotensinogen did not differ between women with and without severe hypoglycaemia during pregnancy. Multivariate regression analysis identified a positive association between rate of severe hypoglycaemia the year preceding pregnancy and postpartum ACE activity (relative rate of severe hypoglycaemia above versus below median ACE activity: 4.4 (CI: 1.7-11.9), p=0.003). No association was found between severe hypoglycaemia during pregnancy and renin angiotensin system activity at 8 weeks., Conclusions: In early pregnancy increased RAS activity does not explain the 5-fold increase in severe hypoglycaemia in women with T1DM. A positive association between occurrence of severe hypoglycaemia and ACE activity outside pregnancy was demonstrated.

Aims: Hypoglycaemia-induced cardiac arrhythmias may be involved in the pathogenesis of the 'dead-in-bed syndrome' in patients with type 1 diabetes. Evidence suggests that the renin-angiotensin system (RAS) influences the occurrence of arrhythmias. The aim of this study was to explore if basal RAS activity affects cardiac repolarization during hypoglycaemia, thereby potentially carrying prognostic information on risk of the 'dead-in-bed syndrome'., Methods and Results: Nine subjects with high RAS activity and nine subjects with low RAS activity were subjected to single-blinded placebo-controlled hypoglycaemia (nadir plasma glucose 2.4 mmol/L). QTc/QTcF and QT dynamics were registered by Holter monitoring. QTc prolonged during [8 (+/-2.3) ms, P < 0.01] and after [11 (+/-3) ms, P < 0.001] hypoglycaemia. Dynamic QT parameters reacted ambiguously. Low RAS activity was associated with a slightly more pronounced QT prolongation [6 (+/-3) ms, P = 0.04]. Adrenaline tended to increase more in the low-RAS group (P = 0.08) and was correlated to QTc (r = 0.67, P < 0.01) and QTcF (r = 0.58, P < 0.05) during hypoglycaemia., Conclusion: Low basal RAS activity may be associated with a slightly more pronounced QT prolongation during hypoglycaemia, when compared with high RAS activity. The impact, however, is modest and the clinical consequence is unclear.

Aims: Severe hypoglycaemia is a significant problem in pregnant women with Type 1 diabetes. We explored whether frequent severe hypoglycaemia during pregnancy in women with Type 1 diabetes is related to placental growth hormone (GH) and insulin-like growth factor I (IGF-I) levels., Methods: A prospective, observational study of 107 consecutive pregnant women with Type 1 diabetes. Blood samples were drawn for IGF-I and placental GH analyses at 8, 14, 21, 27 and 33 weeks. Severe hypoglycaemic events were reported within 24 h., Results: Eleven women (10%) experienced frequent severe hypoglycaemia (> or = 5 events), accounting for 60% of all events. Throughout pregnancy, IGF-I levels were 25% lower in these women (P < 0.005) compared with the remaining women, despite similar placental GH levels. Eighty per cent of the severe hypoglycaemic events occurred before 20 weeks when IGF-I levels were at their lowest. This finding was not explained by differences in insulin dose, median plasma glucose levels or glycated haemoglobin. History of severe hypoglycaemia the year preceding pregnancy and impaired hypoglycaemia awareness-being the only predictors of frequent severe hypoglycaemia in a logistic regression analysis-were not associated with IGF-I or placental GH levels at 8 weeks., Conclusions: In women with Type 1 diabetes experiencing frequent severe hypoglycaemia during pregnancy, IGF-I levels are significantly lower compared with the remaining women despite similar placental GH levels. IGF-I levels are lowest in early pregnancy where the incidence of severe hypoglycaemia is highest. IGF-I may be a novel factor of interest in the investigation of severe hypoglycaemia in patients with Type 1 diabetes.

Background: Varenicline is a new drug indicated for smoking cessation. It has primarily been investigated in healthy adults. The commonest side-effects are nausea, headache, sleep disturbance, constipation, flatulence and vomiting. Hypoglycaemia has not been reported. As smoking cessation is important to reduce risk of cardiovascular morbidity, especially in diabetes, use of effective drugs indicated for smoking cessation is rational., Case Report: We report multiple episodes of severe hypoglycaemia after starting varenicline in a 53-year-old woman with Type 1 diabetes. Since onset of diabetes at age 25 years and until start of varenicline therapy, she had only experienced one episode of severe hypoglycaemia and hypoglycaemia awareness was not impaired. The severe hypoglycaemic episodes disappeared after withdrawal of varenicline., Conclusions: We recommend cautious prescription of varenicline, intensified blood glucose monitoring and careful education of patients with diabetes treated with varenicline. Further investigation of the use of varenicline in patients with diabetes is warranted.

Brain-derived natriuretic peptide (BNP) is a cardioprotective peptide released, together with the inactive NH(2)-terminal part of its prohormone (NT-pro-BNP), in response to different kinds of myocardial stress. Hypoglycemia and hypoxemia are conditions that threaten cellular function and hence potentially stimulate BNP release. BNP interacts with the renin-angiotensin system (RAS). The aim of this study was, therefore, to explore if basal RAS activity has an impact on NT-pro-BNP concentrations during myocardial stress induced by hypoglycemia and hypoxemia. From a cohort of 303 healthy young men, 10 subjects with high-RAS activity and 10 subjects with low-RAS activity (age 26 +/- 1 yr; mean +/- SE) were studied in a single-blinded, randomized, counterbalanced, crossover study on three occasions separated by at least 3 wk: 1) hypoglycemia (mean nadir plasma glucose 2.7 +/- 0.5 mmol/l), 2) hypoxemia (mean nadir Po(2) 5.8 +/- 0.5 kPa), and 3) normoglycemic normoxia (control). NT-pro-BNP was measured at baseline, during the stimuli, and in the recovery phase. Hypoxemia was associated with a 9% increase in NT-pro-BNP from 2.2 +/- 1.5 pmol/l at baseline to 2.4 +/- 1.5 pmol/l during hypoxemia (P < 0.001). Hypoglycemia did not affect the NT-pro-BNP level. RAS activity had no impact on NT-pro-BNP levels during hypoglycemia and hypoxemia. Hypoxemia, but not hypoglycemia, stimulates NT-pro-BNP. This indicates that cardiac defense mechanisms against hypoglycemia, if any, are probably different from those against hypoxemia. Basal RAS activity had no impact on NT-pro-BNP levels.

Introduction: In type 1 diabetes increased risk of severe hypoglycaemia is associated with high angiotensin-converting enzyme (ACE) activity. We tested in healthy humans the hypothesis that this association is explained by the reduced ability of subjects with high ACE activity to maintain normal cognitive function during hypoglycaemia., Methods: Sixteen healthy volunteers selected by either particularly high or low serum ACE activity were subjected to hypoglycaemia (plasma glucose 2.7 mmol/L). Cognitive function was assessed by choice reaction tests., Results: Despite a similar hypoglycaemic stimulus in the two groups, only the group with high ACE activity showed significant deterioration in cognitive performance during hypoglycaemia. In the high ACE group mean reaction time (MRT) in the most complex choice reaction task was prolonged and error rate (ER) was increased in contrast to the low ACE group. The total hypoglycaemic symptom response was greater in the high ACE group than in the low ACE group (p=0.031). There were no differences in responses of counterregulatory hormones or in concentrations of substrates between the groups., Conclusion: Healthy humans with high ACE activity are more susceptible to cognitive dysfunction and report higher symptom scores during mild hypoglycaemia than subjects with low ACE activity.

Background: The deletion-allele of the angiotensin-converting enzyme (ACE) gene and elevated ACE activity are associated with increased risk of severe hypoglycemia in type 1 diabetes. We explored whether genetic and phenotypic variations in other components of the renin-angiotensin system are similarly associated., Methods: Episodes of severe hypoglycemia were recorded in 171 consecutive type 1 diabetic outpatients during a 1-year follow-up. Participants were characterized at baseline by gene polymorphisms in angiotensinogen, ACE, angiotensin-II receptor types 1 (AT1R) and 2 (AT2R), and by plasma angiotensinogen concentration and serum ACE activity., Results: Three risk factors for severe hypoglycemia were identified: plasma angiotensinogen concentration in the upper quartile (relative rate [RR] vs. lower quartile 3.1, 95% confidence interval [CI,] 1.4-6.8), serum ACE activity in the upper quartile (RR vs. lower quartile 2.9, 95% CI, 1.3-6.2), and homo- or hemizygosity for the A-allele of the X chromosome-located AT2R 1675G/A polymorphism (RR vs. noncarriers 2.5, 95% CI, 1.4-5.0). The three risk factors contributed independently to prediction of severe hypoglycemia. A backward multiple regression analysis identified a high number of renin-angiotensin system-related risk factors and reduced ability to perceive hypoglycemic warning symptoms (impaired hypoglycemia awareness) as predictors of severe hypoglycemia., Conclusions: High renin-angiotensin system activity and the A-allele of the AT2R 1675G/A polymorphism associate with high risk of severe hypoglycemia in type 1 diabetes. A potential preventive effect of renin-angiotensin system blocking drugs in patients with recurrent severe hypoglycemia merits further investigation.

Intensive treatment regimens including early initiation of insulin treatment are important to prevent late complications in type 2 diabetes. The assumed risk of severe hypoglycemia (SH) is a major barrier to initiation of insulin treatment. To assess the relevance of this risk we evaluated the frequency of SH as reported in the literature. Using Medline and Embase search we identified 11 studies (5 retrospective and 6 prospective) including at least 50 patients with insulin-treated type 2 diabetes followed for at least 6 months in which frequency of SH was reported. The incidence of SH in the retrospective studies varied from 15 to 73 episodes per 100 patient-year with a proportion of the patients having one or more episodes between 1.4 to 15%. In the prospective studies, both incidence rate and proportion of the patients having one or more episodes of SH were lower than in the retrospective studies. Only few studies looked into the impact of risk factors on the rate of SH. Impaired hypoglycemia awareness, high age, long duration of diabetes and insulin therapy increased the risk, while no association was found with HbA1c and insulin dose. The present knowledge of SH in insulin-treated type 2 diabetes is characterized by the paucity of data and the heterogeneity of the few studies available. Large and long-lasting studies with SH as primary endpoint are warranted in order to further clarify the occurrence of SH and influence of the risk factors in unselected patients with insulin-treated type 2 diabetes.

Aims: The reported risk of severe hypoglycaemia in insulin-treated Type 2 diabetes is highly variable and few studies have evaluated the influence of risk factors. We assessed the incidence and the influence of potential risk factors for severe hypoglycaemia in a questionnaire survey in subjects with insulin-treated Type 2 diabetes receiving currently recommended multifactorial intervention., Methods: Consecutive patients with insulin-treated Type 2 diabetes (n = 401) completed a questionnaire about occurrence of hypoglycaemia in the past, hypoglycaemia awareness and socio-demographic factors. A zero-inflated negative binomial model was used to assess the influence of potential risk factors on the rate of severe hypoglycaemia., Results: The overall incidence of severe hypoglycaemia in the preceding year was 0.44 episodes/person year. Sixty-six (16.5%) patients had experienced at least one event. The risk of any episode of severe hypoglycaemia positively correlated with impaired hypoglycaemia awareness, being married and long duration of diabetes. The risk of repeated episodes of severe hypoglycaemia positively correlated with the presence of peripheral neuropathy, while long duration of diabetes prior to insulin treatment and treatment with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor antagonists (ARBs) were associated with reduced risk. C-peptide concentration and HbA1c were not associated with the risk of severe hypoglycaemia., Conclusions: In this cohort of insulin-treated Type 2 diabetic patients, the incidence of severe hypoglycaemia is higher than reported in most studies, corresponding to about one-third of that in Type 1 diabetes. Impaired hypoglycaemia awareness is the most important risk factor for severe hypoglycaemia.

Aim: Continuous glucose monitoring may reveal episodes of unrecognized hypoglycaemia. We evaluated reproducibility and reliability of hypoglycaemic episodes recorded in daily life by the Medtronic MiniMed Continuous Glucose Monitoring System (CGMS)., Methods: Twenty-nine adult patients with Type 1 diabetes underwent 6 days of continuous subcutaneous glucose monitoring, applying one CGMS on each side of the abdomen. Blood glucose was measured by HemoCue B-Glucose Analyzers six times daily and two different 4-point calibration sets were generated (set A and B). Using these calibration sets, CGMS raw data were recalibrated generating four different CGMS data sets [left-A (left side of abdomen, calibration set A), left-B, right-A and right-B]. Agreement between CGMS data sets was evaluated during hypoglycaemic events, comparing CGMS readings = 2.2 mmol/l with nadir values from corresponding CGMS data sets. CGMS readings were also compared with independent self-monitored blood glucose (SMBG) values., Results: With hypoglycaemia (CGMS readings = 2.2 mmol/l) in calibration set left-A, values below 3.5 mmol/l were present in 99% (95% CI: 95-100%) of samples in left-B, 91% (95% CI: 84-96%) of samples in right-A, and 90% (95% CI: 83-95%) of samples in right B. In 84% of these episodes (95% CI: 59-96%) independent SMBG values were below 3.5 mmol/l. Difference in duration was observed with a median difference of 20 min; (left-A vs. right-B)., Conclusion: Hypoglycaemic episodes recorded by CGMS are reproducible and agreement with independent SMBG values is acceptable for retrospective recording of hypoglycaemic events with CGMS.

Aims/hypothesis: Plasma semicarbazide-sensitive amine oxidase (SSAO) is elevated in patients with type 1 and type 2 diabetes and has been implicated in the pathophysiology of diabetic late complications. The regulation of SSAO production remains unknown. We studied correlations between plasma SSAO activity and parameters associated with diabetic late complications., Methods: Plasma SSAO was measured in a well-characterised group of 287 patients with type 1 diabetes. Standard statistical methods were used to investigate correlations with clinical parameters and components of the renin-angiotensin system., Results: Overall, plasma SSAO was elevated, at 693+/-196 mU/l (mean+/-SD; normal controls 352+/-102 mU/l). Plasma SSAO was higher in the group with late complications or hypertension, and in patients treated with ACE-inhibitors. In univariate analysis a significant positive correlation (p<0.001, r=0.27) was found between plasma SSAO and serum ACE activity in patients untreated with ACE inhibitors or angiotensin II receptor antagonists (n=221), but plasma SSAO did not differ by ACE I/D genotype. Plasma SSAO correlated positively with duration of diabetes, HbA(1)c and plasma renin, and negatively with plasma angiotensinogen and body mass index. A multiple regression analysis including these variables resulted in serum ACE activity (p<0.001), ACE genotype (negatively, p<0.001) and HbA(1)c (p=0.023) as explaining variables., Conclusions/interpretation: Results suggest that a common factor is involved in the regulation of both plasma SSAO and serum ACE, which is different from the genetic determination of ACE activity.

Background: Differences between studies in rates of severe hypoglycaemia in type 1 diabetic cohorts are common and poorly understood. The purpose of this study was to assess the frequency of severe hypoglycaemia in unselected patients treated in different secondary care centres and to evaluate the influence of risk markers, clinical setting and selection., Methods: Cross-sectional Danish-British multicentre survey of 1076 consecutive adult patients with clinical type 1 diabetes who completed a detailed questionnaire on hypoglycaemia and related issues. Key variable was the self-reported rate of severe hypoglycaemia during the preceding year., Results: The overall rate of severe hypoglycaemia in the preceding year was 1.3 episodes/patient-year and episodes were reported by 36.7% of subjects. The distribution was highly skewed with 5% of subjects accounting for 54% of all episodes. There were no significant differences between countries or centres. Reduced hypoglycaemia awareness, peripheral neuropathy and smoking were the only significant risk markers of severe hypoglycaemia in a stepwise multivariate analysis. In a subgroup selected to be similar to the Diabetes Control and Complications Trial (DCCT) cohort, the rate of severe hypoglycaemia was 0.35 episodes/patient-year and only retinopathy was a significant risk marker together with state of awareness., Conclusion: Severe hypoglycaemia remains a significant clinical problem in type 1 diabetes. The rate of severe hypoglycaemia and the influence of risk markers are very sensitive to selection and differences in rates between centres or studies seem to disappear after correction for differences in clinical characteristics. Smoking is a novel overall risk marker of severe hypoglycaemia., (Copyright 2004 John Wiley & Sons, Ltd.)

Introduction: Screening for diabetic retinopathy in a Danish county--are we following the recommendations? Incidence and risk factors of development and progression of diabetic retinopathy and prevalence of blindness among type 1 diabetics consulting the hospital of Hillerød are being described., Material and Methods: A total of 223 type 1 diabetics (debut < 30 years of age, insulin treated from first year of diagnosis) identified in a cross-sectional study in 1993 and followed until 2000 when data from last examination in the diabetes out-patient clinic and the ophthalmology clinic are registered., Results: Ophthalmologists have screened nearly 97% of the patients as stated in the recommendations of the department. Only 2% were blind and only one patient went blind during the study period. The incidence of development of retinopathy was (54/119) 45%, (14/104) 13% had improved, (77/194) 40% had a progression of retinopathy, and (30/194) 15% had progressed to proliferative retinopathy. Risk factors found in the study match previously described risk factors., Discussion: Audits encourage the implementation of screening programmes and hence reduce sight threatening diabetic retinopathy. The results of the study emphasize the importance of close co-operation between diabetes out-patient clinics and ophthalmologists and the necessity of regular screening. More audits are needed to bring screening for diabetic eye disease into focus and decrease the number of weak-sighted and blind diabetics.

Background: The ability of people with insulin-treated diabetes to remember severe hypoglycaemia and the consistency of their self-estimated awareness of hypoglycaemia are not well documented but are important in clinical practice. The aim of this study is to assess recall of severe hypoglycaemia in patients with type 1 diabetes and to evaluate the feasibility of a simple method for clinical classification of the awareness of hypoglycaemia., Methods: A one-year prospective study was performed on a cohort of patients with type 1 diabetes (n = 230). The rate of severe hypoglycaemia reported retrospectively at the end of the study was compared to the prospectively recorded rate during the study period. Self-estimated awareness was explored in questionnaires at baseline and at the end, and assessments were evaluated by the occurrence of severe hypoglycaemic episodes., Results: Almost 90% of the participants correctly recalled whether they had had severe hypoglycaemia. However, those with high prospectively recorded numbers had incomplete recall, resulting in a 15% underestimation of the overall rate. On the basis of the answer to the question "Do you recognise symptoms when you have a hypo?", the population was classified into three groups: 40% with normal awareness, 47% with impaired awareness and 13% with unawareness. The groups with impaired awareness and unawareness had 5.1 and 9.6 times higher rates of severe hypoglycaemia, respectively, compared to the group with normal awareness (p < 0.001)., Conclusion: People with type 1 diabetes generally remember severe hypoglycaemic episodes during a one-year period. A simple method is proposed for classifying the state of awareness of hypoglycaemia in clinical practice., (Copyright 2003 John Wiley & Sons, Ltd.)

The E23K polymorphism of the pancreatic beta-cell ATP-sensitive K(+) (K(ATP)) channel subunit Kir6.2 (KCNJ11) is associated with type 2 diabetes in whites, and a recent in vitro study of the E23K variant suggests that the association to diabetes might be explained by a slight inhibition of serum insulin release. In a study comprising 519 unrelated glucose-tolerant subjects, we addressed the question as to whether the E23K variant was related to reduced serum insulin release during an oral glucose tolerance test (OGTT). Furthermore, the polymorphism was examined in a case-control study comprising 803 type 2 diabetic patients and 862 glucose-tolerant control subjects. The E23K variant was associated with significant reductions in the insulinogenic index (P = 0.022) and serum insulin levels under the response curve during an OGTT (0-120 min) (P = 0.014) as well as with an increase in BMI (P = 0.013). In the present study, the association of the E23K polymorphism with type 2 diabetes was not significant (P = 0.26). However, the K23K genotype significantly associated with type 2 diabetes in a meta-analysis of white case and control subjects (n = 2,824, odds ratio [OR] 1.49, P = 0.00022). In conclusion, the widespread E23K polymorphism may have a diabetogenic effect by impairing glucose-induced insulin release and increasing BMI.

Aims/hypothesis: We have previously shown a strong relationship between high angiotensin-converting enzyme (ACE) activity, presence of the deletion (D) allele of the ACEgene and recall of severe hypoglycaemic events in patients with Type 1 diabetes. This study was carried out to assess this relationship prospectively., Methods: We followed 171 adult outpatients with Type 1 diabetes in a one-year observational study with the recording of severe hypoglycaemia. Participants were characterised by serum ACE activity and ACE genotype and not treated with ACE inhibitors or angiotensin II receptor antagonists., Results: There was a positive relationship between serum ACE activity and rate of severe hypoglycaemia with a 2.7 times higher rate in the fourth quartile of ACE activity compared to the first quartile (p=0.0007). A similar relationship was observed for the subset of episodes with coma (2.9 times higher rate in fourth quartile compared to first quartile; p=0.048). The impact of serum ACE activity was most pronounced in C-peptide negative subjects (4.2 times higher rate in fourth quartile compared to first quartile; p=0.003), and in this subgroup carriers of the D allele of the ACEgene had higher rates of severe hypoglycaemia compared to the group homozygous for the insertion (I) allele. In a multiple regression analysis high serum ACE activity and impaired awareness of hypoglycaemia were identified as the only significant predictors of severe hypoglycemia., Conclusion: High ACE activity and the presence of the D allele of the ACE gene predict a high rate of severe hypoglycaemia in Type 1 diabetes.

Background: The insertion (I) allele of the angiotensin-converting-enzyme (ACE) gene occurs at increased frequency in endurance athletes. This association suggests that low ACE activity is favourable for performance in conditions with limited substrate availability. Such conditions occur in endurance athletes during competition and in diabetic patients during insulin-induced hypoglycaemia. Patients rely on preserved functional capacity to recognise hypoglycaemic episodes and avoid progression by self-treatment. We studied whether ACE activity is related to the risk of severe hypoglycaemia in type 1 diabetes., Methods: Consecutive adult outpatients with type 1 diabetes, untreated with ACE inhibitors or angiotensin-II-receptor antagonists (n=207) reported their experience of mild and severe hypoglycaemia during the previous 1 year and 2 years. The patients were further characterised by diabetes history, degree of hypoglycaemia awareness, measurement of C-peptide, haemoglobin A(1c), and serum ACE concentrations, and determination of ACE genotype., Findings: Patients with the DD genotype had a relative risk of severe hypoglycaemia in the preceding 2 years of 3.2 (95% CI 1.4-7.4) compared with those who had the II genotype. There was a significant relation between serum ACE activity and the rate of severe hypoglycaemia (relative risk per 10 U/L increment 1.4 [1.2-1.6]), corresponding to a 3.5 times higher risk for patients in the highest quartile than for those in the lowest quartile. Multiple regression analysis showed that the effect of the ACE genotype was explained by its influence on serum ACE activity and that the only other significant determinants of the risk of severe hypoglycaemia were the degree of hypoglycaemia awareness, b-cell function, and duration of diabetes of more than 20 years., Interpretation: ACE activity is a clinically significant marker of the risk of severe hypoglycaemia in patients with type 1 diabetes, especially in those with impaired defence against hypoglycaemia. These findings need to be confirmed in prospective studies.

In order to define prevalence and incidence of diabetes mellitus in cystic fibrosis, we followed 191 unselected patients above two years of age (median 13.6) in a five-year prospective study with annual oral glucose tolerance tests. The prevalence of diabetes increased from 11 to 24% during the study period with an annual age-dependent incidence rate of 4-9%. Diabetes was diagnosed at a median age of 21 years (range 3-40). At diagnosis of diabetes, hyperglycaemia, fasting hyperglycaemia (> or = 7.8 mmol/l), and increased haemoglobin Alc levels (> 6.4) were present in 33%, 16% and 16% of the diabetic patients, respectively. Impaired glucose tolerance implied a higher risk than normal glucose tolerance for the development of diabetes (odds ratio 5.6). In 58% of cases with impaired glucose tolerance, however, glucose tolerance was normalised at the next annual test. Normal glucose tolerance was found in only 37% of the patients at all five tests. Within this group of patients, median fasting and two-hour post-load plasma glucose concentrations and haemoglobin Alc levels increased by 6-8% during five years. Thus, the prevalence and incidence of diabetes in patients with cystic fibrosis is very high and increases with age. Since symptoms of hyperglycaemia and increased fasting plasma glucose and haemoglobin Alc levels are inconstant findings in newly diagnosed diabetic cystic fibrosis patients, we recommend annual oral glucose tolerance tests in all cystic fibrosis patients above the age of 10 years.

A review of the literature on pituitary function in haemochromatosis is presented. In morphological studies pituitary iron deposition, in particular in gonadotropic cells, has been demonstrated. In a number of case series, insufficiency of pituitary gonadotropic secretion with clinical hypogonadism was observed in 46% of the patients. Overt insufficiency of the other hormonal axes was infrequent. However, subclinical insufficiency of the growth hormone axis was present in 15%, of the lactotropic axis in 8%, of the thyroid axis in 4% and of the adrenocortical axis in 1.5% of the patients. Lactotropic, thyroid or adrenocortical insufficiency was usually associated with hypogonadism or growth hormone insufficiency. Investigation of pituitary function (in first line the gonadotropic and the somatotropic function) in patients with primary or secondary haemochromatosis is recommended on wide indications, in order to initiate relevant substitution therapy.

Objective: We studied glucose metabolism and insulin kinetics in cystic fibrosis patients with diabetic and normal glucose tolerance., Design: Measurements of blood glucose and serum free insulin concentrations during hyperinsulinaemic normoglycaemic clamp and post-clamp insulin decay, followed by the calculation of insulin sensitivity (M-value and M/I ratio), insulin clearance rate, serum half-life and apparent distribution space for insulin., Subjects: Cystic fibrosis patients, age range 20-29 years, with diabetes mellitus (n = 10) and normal glucose tolerance (n = 10), and 10 age-matched control subjects., Results: During the glucose clamp, diabetic cystic fibrosis patients needed less glucose than cystic fibrosis patients with normal glucose tolerance and control subjects (M-value), and steady-state serum insulin concentrations were lower in cystic fibrosis patients with diabetic and normal glucose tolerance than in control subjects. The quantity of glucose metabolized per unit of serum insulin concentration (M/I ratio) was similar in the three study groups (median approximately 145 (mumol/kg/min)/(nmol/l); range 70-252). Insulin clearance rates were higher in cystic fibrosis patients with diabetic (24.4 (19.3-29.9) ml/kg/min) and normal (22.6 (14.9-28.4) ml/kg/min) glucose tolerance than in control subjects (17.5 (15.9-24.2) ml/kg/min). Although insulin clearance rates were inversely related to body mass index (R(S) = -0.59, P < 0.001), the higher insulin clearance rates in CF patients cannot be accounted for solely by differences in body mass index since the insulin clearance rates were similarly increased in patients with body mass index above and below 20 kg/m2 (22.7 (14.9-28.4) and 24.4 (19.3-29.9) ml/kg/min, respectively). Serum half-lives for insulin were shorter in cystic fibrosis patients (approximately 4.3 (3.2-7.2) min) than in control subjects (5.9 (3.8-12.5) min), whereas the apparent distribution spaces for insulin were similar in the three study groups (approximately 150 (88-391) ml/kg)., Conclusions: Insulin sensitivity, calculated as the quantity of glucose metabolized per kg body weight per unit of serum insulin concentration, is normal in cystic fibrosis patients with normal glucose tolerance and with well controlled diabetes mellitus. The insulin clearance rate is increased in cystic fibrosis patients with diabetic and normal glucose tolerance, owing to a shorter serum half-life of insulin, whereas the apparent distribution space for insulin is normal.

Pancreatic and gut hormone responses to oral glucose, and insulin sensitivity were studied in cystic fibrosis patients with normal (N = 14), impaired (N = 4), and diabetic (N = 12) glucose tolerance, and in 10 control subjects, and beta cell responses to oral glucose and intravenous glucagon were compared. Compared to control subjects, initial insulin and C-peptide responses to oral glucose were lower in all patient groups, and decreased with decreasing glucose tolerance. Insulin sensitivity in patients with impaired and diabetic glucose tolerance was lower than in control subjects. The 6 min post-glucagon C-peptide concentration was positively correlated with the initial insulin response to oral glucose. Fasting levels of pancreatic polypeptide, pancreatic glucagon, total glucagon, glucagon-like peptide-1 7-36 amide, and gastric inhibitory polypeptide were normal in all patient groups. Following oral glucose, pancreatic polypeptide responses were absent in all patients, suppressibility of pancreatic glucagon secretion was increasingly impaired with decreasing glucose tolerance, and gut hormone levels were normal. In conclusion, at cystic fibrosis (a) insulin secretion is impaired even when glucose tolerance and insulin sensitivity are within the normal range, (b) the glucagon test gives valid estimates of residual beta cell function, (c) pancreatic polypeptide response to oral glucose is absent, (d) glucagon suppressibility decreases with decreasing glucose tolerance, and (e) the enteroinsular axis is intact.

The impact of pre-diabetes on clinical status was retrospectively studied in 38 cystic fibrosis (CF) patients with diabetes mellitus (DM) and 38 non-diabetic CF patients (control patients), matched in pairs for age, sex, and chronic Pseudomonas aeruginosa lung infection. Quarterly parameters of CF clinical status were collected for 6 years prior to the diagnosis of DM in the index case. Compared to the control patients, decreases in body weight, body mass index (BMI), forced expiratory volume in 1s (FEV1), and forced vital capacity (FVC) and an increase in the daily intake of pancreatic enzyme capsules were found in the pre-diabetic patients. Statistically significant differences in body weight, BMI, FEV1, FVC, and intake of pancreatic enzyme capsules between pre-diabetic and control patients emerged 4, 4, 1.25, 3 and 4.5 years prior to the diagnosis of DM, respectively. The number of lung infections did not differ between the two groups of patients. Thus, when DM develops in CF patients, an insidious decline in overall clinical status is observed for years prior to its diagnosis. Whether clinical deterioration in CF leads to DM, or pre-diabetes results in declining CF clinical status is presently unknown. Accumulating evidence suggests that the latter may be the case since insulin therapy seems to improve lung function in CF.

The relationship between the cystic fibrosis (CF) genotype and endocrine and exocrine pancreatic function was studied in 215 CF patients. In the 211 patients with the delta F508 mutation, endocrine pancreatic function (oral glucose tolerance; WHO criteria) was normal in 72.5%, impaired in 12.3%, and diabetic in 15.2% of the patients, with no difference between CF patients homozygous (N = 163, median age 15 years, range 2-40) or heterozygous (N = 48, 18 years, 3-40; age difference not significant) for the delta F508 mutation. Exocrine pancreatic sufficiency (no need for pancreatic enzyme substitution) was found in 0.6% of the patients homozygous for the delta F508 mutation and in 10.4% of the heterozygotes (p less than 0.01). Homozygous patients with pancreatic insufficiency took more pancreatic enzyme capsules (median 42 per day, range 0-192) than the heterozygotes (29 per day, 0-300; p less than 0.001). The four patients (1.9%) without the delta F508 mutation had normal glucose tolerance but exocrine pancreatic insufficiency. In conclusion, the major mutation genotype in CF (delta F508) affects the severity of the exocrine pancreatic insufficiency, whereas endocrine pancreatic function is unrelated to this genotype.

The general use of first order kinetics to describe the disappearance of insulin from plasma in man contrasts the available evidence of saturation kinetics for insulin. In order to bridge this gap, we have put forward three alternative models of insulin kinetics. Model 1 considers the combined existence of first order and saturation (Michaëlis-Menten) kinetics. Model 2 considers saturation kinetics alone. Model 3 considers first order kinetics alone. The validity of the models was studied in normal and type I (insulin-dependent) diabetic subjects. Sequential constant intravenous infusions of insulin at different rates were used to achieve different levels of steady state plasma insulin concentrations, while the glycaemic level (usually normoglycaemia) was maintained by a glucose clamp. Appropriate validation procedures demonstrated that the model of saturation kinetics alone (model 2) was superior to the other models in normal subjects at physiological and supraphysiological plasma insulin concentrations, and in diabetic patients at supraphysiological concentrations. The minimal model at physiological insulin concentrations in type I diabetic patients was that of first order kinetics (model 3). The kinetics of insulin was independent of the species of insulin (human or porcine) in both study groups. The actual glycaemic clamp level (normoglycaemia and moderate hyperglycaemia) did not influence the insulin disappearance rate. Binding of insulin to its receptor is considered to be the initial step in insulin degradation. Saturation kinetics of insulin may therefore be influenced by the saturation of binding of insulin molecules to their receptors. We found values of Km (i.e. the concentration of plasma insulin at which the insulin disappearance rate is half maximal) in normal subjects comparable to values of Kd (i.e. the dissociation constant for insulin-receptor binding) from receptor studies in isolated cells. Changes in regional (hepatic and/or renal) blood flow at hyperinsulinaemia represent an alternative explanation to a model of saturation kinetics. Increases in Vmax (i.e. the maximal insulin disappearance rate) and Km with increasing insulin dose were observed in normal subjects. This finding suggests that insulin may disappear from plasma by more than one saturable pathway. Additional studies are needed to confirm this observation. The clearance rate of insulin at infinitesimal plasma insulin concentrations (Vmax/Km) was 28 +/- 8 ml.kg-1.min-1 in normal subjects. This value is higher than most clearance rates previously reported in studies using first order kinetics. The clearance rate of insulin in type I diabetic patients was 20 +/- 4 ml.kg-1.min-1, corresponding to a reduction in clearance of 30% compared to normal subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Three theoretical kinetic models for plasma disappearance of insulin were examined in six normal men. The models allowed for the existence of non-saturable and/or saturable mechanisms. Constant infusion of porcine insulin at different rates was used to achieve different levels of steady state plasma insulin concentrations, while normoglycaemia was secured by a glucose clamp technique. Appropriate validation procedures demonstrated that one of the three models was superior to the others in describing the relationship between the exogenous insulin infusion rate Iex and the steady state plasma insulin concentration C: Iex = -Iend + k2 X C/(k3 + C), where Iend is the endogenous post-hepatic insulin delivery rate. Thus, only saturable mechanism(s) could be demonstrated. The median value of k2 (the maximal insulin disappearance rate) and k3 (the plasma insulin concentration at which the insulin disappearance rate is half maximal) were 7.31 nmol X min.-1 and 3.89 nmol X 1-1. The median value of k2/k3 (the clearance rate of insulin for infinitesimal plasma insulin concentrations) was 25.0 ml X kg-1 X min.-1. Thus, at physiological levels of plasma insulin concentrations the metabolic clearance rate of insulin is higher than insulin clearance estimates previously reported in studies based on the assumption of first order kinetics.

The influence of the actual glycaemic level on the kinetics of insulin disappearance from plasma was studied in 16 type I diabetic patients. Constant intravenous infusion of insulin (1-5 mU.kg-1.min.-1) was used to achieve different levels of steady state plasma free insulin concentrations, while the blood glucose level was clamped at normoglycaemia, 4.1 +/- 0.1 mmol/l (mean +/- S.E.M.), and mild hyperglycaemia, 8.2 +/- 0.1 mmol/l. The experimentally determined data were compared using a previously validated model of first order kinetics for insulin disappearance from plasma in diabetic patients. At the physiological insulin concentration range the median clearance rate of insulin was 23 ml.kg-1.min-1 (range 16-26) at normoglycaemia and 23 ml.kg-1.min-1 (19-35) at hyperglycaemia (P = 0.45). At supraphysiological levels, insulin was cleared at a lower rate at normoglycaemia than at hyperglycaemia. No correlation was observed between the insulin clearance rate and the duration of diabetes or the haemoglobin A1C level (both Spearman's rho = 0.08). In conclusion, the insulin clearance rate from plasma is independent of the actual glycaemic level and hardly influenced by the long-term glycaemic level in type I diabetic patients.

Three women with insulin-dependent diabetes mellitus (IDDM) from childhood and early development of diabetic retinopathy are described. Insulin requirement was reduced to 5-12 IU daily in all three after relatively uncomplicated births and all had very brittle diabetes on this dosage. At re-examination 16-22 years after these births and after 34-42 years of IDDM, regression of retinopathy was observed in two patients, while the third had a light retinopathy at the same level as initially. Other diabetic complications were few and none of the patients had nephropathy. Pituitary examination revealed incomplete hypopituitarism in all cases, human growth hormone (HGH) being the sole common factor lacking. These findings and a review of four similar cases reported previously lend some support to the hypothesis of HGH as a possible pathogenetic co-determinant in the development of diabetic retinopathy.

To investigate the mechanism of insulin degradation in normal subjects, a kinetic model of insulin disappearance was constructed: insulin was assumed to be extracted from plasma by two independent processes, one saturable and one non-saturable. On the basis of these assumptions, a linear (non-proportional) relationship between steady-state plasma insulin concentration and steady-state plasma disappearance rate was predicted over the concentration range studied. Constant infusion experiments were performed on eight healthy normal subjects, normoglycaemia and fasting plasma C-peptide concentrations being maintained during the experiments. Agreement was found between the predictions of the model and the experimental results, and it is concluded that insulin degradation in normal subjects may be described in terms of two processes: one that is saturated at physiological plasma insulin concentrations and one that is apparently non-saturable over a wide concentration range.

Absorption of subcutaneously injected soluble insulin deviates markedly from simple first-order kinetics and depends both on the volume and concentration of the injected solution. This paper presents a model of the absorption process in which insulin is presumed to be present in subcutis in a low molecular weight form, a high molecular weight form, and an immobile form where the molecules are bound to the tissue. The model describes how diffusion and absorption gradually reduce the insulin concentrations in the subcutaneous depot and thereby shift the balance between the three forms in accordance with usual laws of chemical kinetics. By presuming that primarily low molecular weight insulin penetrates the capillary walls, the model can account for experimentally observed variations in the absorption rate over a wide range of volumes and of concentrations. The model is used to determine the effective diffusion constant D for insulin in subcutis, the absorption rate constant B for low molecular weight insulin, the equilibrium constant Q between high and low molecular weight insulin, the binding capacity C for insulin in the tissue, and the average life time T for insulin in its bound state. Typical values for a bolus injection in the thigh of fasting type I diabetic patients are D = 0.9 x 10(-4) cm2/min, B = 1.3 X 10(-2)/min, and Q = 0.13 (ml/IU)2. Binding of insulin in the tissue is significant only at small concentrations. The binding capacity is of the order of C = 0.05 IU/cm3 with a typical average life time in the bound state of T = 80.0 min. Combined with a simplified model for distribution and degradation of insulin in the body, the absorption model is used to simulate variations in plasma free insulin concentrations with different delivery schedules, i.e., bolus injection and dosage by means of an infusion pump. The simulations show that a pump repetition frequency of 1-2 per hr is sufficient to secure an almost constant plasma insulin concentration.

The distribution spaces at equilibrium for 3H2O, [14C]urea and s-O-[14C]-methylglucose were measured in white fat cells using centrifugation through silicone oil at 2500 X g; no significant differences were observed. L-[14C]Glucose added immediately before the centrifugation was used as a marker for the extracellular water space. The calculated intracellular water content of the cells after the centrifugation through oil (e.g. 3H2O space minus L-[14C]glucose space) is an unbiased measure of the water content of the fat cells in suspension as judged by the following criteria: (1) The intracellular distribution space for 3-O-[14C]'methylglucose at equilibrium (methylglucose space minus L-glucose space) was not different from that calculated from a methylglucose wash-out curve. (2) The intracellular content of L-[14C]glucose (half time of efflux about 60 min) in cells preloaded during incubation of the tissue with collagenase was not different in cells recovered by (a) centrifugation through oil at 2500 X g, (b) centrifugation through oil at 600 X g, (c) centrifugation at 600 X g in the absence of oil and (d) filtration on Millipore filters. The intracellular content of water determined on cells from single rats weighing 120-150 g was 2.75 +/- 0.55 mul/100 mul fat cells (+/- S.D., n = 30). The intracellular content of potassium, determined on cells from the same rats, was 252 +/- 62 nmols/100 mul fat cells (+/- S.D., n = 30). The concentration of potassium in the intracellular water was calculated as 104 +/- 15 mM (+/- S.D., n = 30).

Human and porcine insulin were infused intravenously at various rates into 4 normal and 6 Type I diabetic subjects, using a double-blind cross-over design and a euglycaemic glucose clamp, to study the relationship between the steady state plasma free insulin concentration and its plasma disappearance rate. By mathematical model validation procedures both human and porcine insulin were found to obey saturation kinetics in normal subjects and first order kinetics in diabetic subjects in the insulin concentration range studied (0-2 nmol/l). No differences in parameters were observed between the two types of insulin in the study groups. The median clearance rate of insulin in normal subjects was 31 ml.kg-1.min-1 at infinitesinal plasma insulin concentrations versus 21 ml.kg-1.min-1 in the diabetic subjects. Thus, at physiological plasma concentrations both human and porcine insulin disappear faster via the saturable mechanism(s) found in normal subjects than via the apparently linear mechanism(s) found in diabetic subjects.

A double-blind cross-over study of the sc absorption of radiolabelled semi-synthetic human (SHI) and purified porcine (PPI) insulin was made. Absorption of both isophane (n = 10) and soluble insulin (n = 8) was studied. There was no significant difference between the disappearance from the injection site, the plasma free insulin concentrations, or blood glucose levels after sc injection of the isophane preparations. A faster disappearance of the soluble SHI (as judged from T/50 and AUC) was found (both P-values less than 0.01). However, no difference was observed between the plasma insulin concentrations at any time point (P less than 0.05). Blood glucose levels showed no statistical differences between the two soluble preparations. The data indicate minor differences between the pharmacokinetics of SHI and PPI, but these seem of no clinical importance.

The C-peptide and insulin secretory responses to increasing doses of iv glucagon (1, 2, 5, 10 micrograms/kg body weight and 1 mg (only diabetics] were investigated in six lean non-insulin-dependent diabetic patients and six normal subjects, matched for body weight and fasting blood glucose concentrations. A well defined relationship between glucagon dose and the C-peptide/insulin response was observed in both groups. The course of the dose-response curves was significantly different in diabetics. The maximal obtainable C-peptide response (E-max) was reduced to 53% of the response in normal subjects (P = 0.037), and the insulin response was reduced to 52% (P = 0.014). E-max was reached in diabetics with only 10 micrograms/kg of glucagon, whereas higher doses seem to be needed in the control group. However, the glucagon dose causing 50% of E-max (ED50) was not significantly higher. Thus, the widely accepted use of 1 mg of glucagon to test residual beta cell function secures a maximal response of both insulin and C-peptide in non-insulin-dependent diabetic subjects. In addition, our data support the theory that beta cell deficiency is a basic feature of non-insulin-dependent diabetes.

We have tested whether our previous finding in normal subjects that the disappearance of insulin from plasma obeys saturation kinetics alone also applies to type I diabetic patients. In six long-term diabetic patients steady state plasma insulin concentrations resulting from constant insulin infusion at different rates were compared with the predictions of three models for the kinetics of insulin in plasma. The models allowed the existence of non-saturable (first order equation) or saturable (Michaëlis-Menten equation) mechanisms, or both. The minimal acceptable model included saturation kinetics alone in four subjects and first order kinetics alone in two subjects. The clearance of insulin in diabetic patients, calculated from the best fitting model, was 18.0 (median, range 10.0-23.7) ml X kg-1 X min.-1 versus 25.0 (18.6-47.1) ml X kg-1 X min.-1 in six normal subjects (2p = 0.008). Insulin thus disappears from plasma at a lower rate in diabetic patients than in normal subjects at physiological plasma concentrations.