Demonstration of increased concentrations of circulating glycated insulin in human Type 2 diabetes using a novel and specific radioimmunoassay

AIMS/HYPOTHESIS: Glycation of insulin, resulting in impaired bioactivity, has been shown within pancreatic beta cells. We have used a novel and specific radioimmunoassay to detect glycated insulin in plasma of Type 2 diabetic subjects. METHODS: Blood samples were collected from 102 Type 2 diabetic patients in three main categories: those with good glycaemic control with a HbA(1c) less than 7%, moderate glycaemic control (HbA(1c) 7-9%) and poor glycaemic control (HBA(1c) greater than 9%). We used 75 age- and sex-matched non-diabetic subjects as controls. Samples were analysed for HbA(1c), glucose and plasma concentrations of glycated insulin and insulin. RESULTS: Glycated insulin was readily detected in control and Type 2 diabetic subjects. The mean circulating concentration of glycated insulin in control subjects was 12.6+/-0.9 pmol/l ( n=75). Glycated insulin in the good, moderate and poorly controlled diabetic groups was increased 2.4-fold ( p<0.001, n=44), 2.2-fold ( p<0.001, n=41) and 1.1-fold ( n=17) corresponding to 29.8+/-5.4, 27.3+/-5.7 and 13.5+/-2.9 pmol/l, respectively. CONCLUSION/INTERPRETATION: Glycated insulin circulates at noticeably increased concentrations in Type 2 diabetic subjects.     

Plasma dipeptidyl peptidase-IV activity in patients with type-2 diabetes mellitus correlates positively with HbAlc levels, but is not acutely affected by food intake

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide are incretin hormones, secreted in response to meal ingestion. The incretin hormones stimulate insulin secretion and are essential for the maintenance of normal plasma glucose concentrations. Both incretin hormones are metabolized quickly by the enzyme dipeptidyl peptidase-IV (DPP-IV). It is well known that type-2 diabetic patients have an impaired incretin effect. Therefore, the aim of the present study was to investigate plasma DPP-IV activity in the fasting and the postprandial state in type-2 diabetic patients and control subjects. DESIGN: The study included two protocols. Protocol one involved 40 fasting type-2 diabetic patients (28 men); age 61 +/- 1.4 (mean +/- s.e.m.) years; body mass index (BMI) 31 +/- 0.6 kg/m(2); HbAlc 7.2 +/- 0.2%; and 20 matched control subjects (14 men) were studied. Protocol two involved eight type-2 diabetic patients (six men); age 63 +/- 1.2 years; BMI 33 +/- 0.5 kg/m(2); HbAlc 7.5 +/- 0.4%; eight matched control subjects were included. METHODS: In protocol one, fasting values of DPP-IV activity were evaluated and in protocol two, postprandial DPP-IV activity during a standard meal test (566 kcal) was estimated. RESULTS: Mean fasting plasma DPP-IV activity (expressed as degradation of GLP-1) was significantly higher in this patient group compared with the control subjects (67.5 +/- 1.9 vs 56.8 +/- 2.2 fmol GLP-1/h (mean +/- s.e.m.); P=0.001). In the type-2 diabetic patients, DPP-IV activity was positively correlated to FPG and HbAlc and negatively to the duration of diabetes and age of the patients. No postprandial changes were seen in plasma DPP-IV activity in any of the groups. CONCLUSIONS: Plasma DPP-IVactivity increases in the fasting state and is positively correlated to FPG and HbAlc levels, but plasma DPP-IV activity is not altered following meal ingestion and acute changes in plasma glucose.     

Differential gene expression of NADPH oxidase (p22phox) and hemoxygenase-1 in patients with Type 2 diabetes and microangiopathy.

AIMS: While the downstream effects of increased reactive oxygen species (ROS) in the pathogenesis of diabetes were well studied, only a few studies have explored the cellular sources of ROS. We examined whether protection against oxidative stress is altered in patients with diabetes and microangiopathy by examining changes in NADPH oxidase (p22(phox)) and hemoxygenase-1 (HO-1) levels. METHODS: NADPH oxidase (p22(phox)) and HO-1 gene expression were probed by RT-PCR using leucocytes from patients with Type 2 diabetes without (n = 19) and with microangiopathy (n = 20) and non-diabetic subjects (n = 17). Levels of lipid peroxidation as measured by thiobarbituric reactive substances (TBARS) and protein carbonyl content (PCO) were determined by fluorimetric and spectrophotometric methods, respectively. RESULTS: p22(phox) gene expression (mean +/- SE) was significantly (P < 0.05) higher in diabetic patients with (0.99 +/- 0.04) and without microangiopathy (0.86 +/- 0.05) compared with control subjects (0.66 +/- 0.05). Consistent with the mRNA data, the p22(phox) protein expression and NADPH oxidase activity was also increased in cells from diabetic patients compared with control subjects. However, HO-1 gene expression was significantly (P < 0.05) lower in patients with (0.73 +/- 0.03) and without microangiopathy (0.85 +/- 0.02) compared with control subjects (1.06 +/- 0.03). The mean (+/- SE) levels of TBARS were significantly (P < 0.05) higher in diabetic patients with (14.36 +/- 1.3 nM/ml) and without microangiopathy (12.20 +/- 1.3 nM/ml) compared with control subjects (8.58 +/- 0.7 nM/ml). The protein carbonyl content was also significantly (P < 0.05) higher in diabetic patients with (1.02 +/- 0.04 nmol/mg protein) and without microangiopathy (0.84 +/- 0.06 nmol/mg protein) compared with control subjects (0.48 +/- 0.02 nmol/mg protein). In diabetic subjects, increased p22(phox) gene expression was negatively correlated with HO-1 and positively correlated with TBARS, PCO, HbA(1c) and diabetes duration. In contrast, HO-1 gene expression was correlated negatively with p22phox, TBARS, PCO, HbA(1c) and diabetes duration. CONCLUSION: Our results indicate that increased oxidative damage is seen in Asian Indians with Type 2 diabetes and microangiopathy and is associated with increased NADPH oxidase (p22(phox)) and decreased HO-1 gene expression.     

Different risk factors for peripheral vascular calcification between diabetic and non-diabetic haemodialysis patients--importance of glycaemic control

AIM/HYPOTHESIS: Although derangements of calcium and phosphate control have been emphasized as important risk factors for vascular calcification in non-diabetic haemodialysis patients, similar risk factors for diabetic haemodialysis patients are not known. We compared factors affecting peripheral vascular calcification between haemodialysis patients with and without diabetes. METHODS: We examined 421 patients on maintenance haemodialysis. There were 89 patients with Type II (non-insulin-dependent) diabetes mellitus (53 men and 36 women, 62+/-10 years old) and 332 patients without diabetes (192 men and 140 women, 59+/-13 years old). Hand roentgenography was carried out, and visible vascular calcification of the hand arteries was evaluated. RESULTS: There were 42 diabetic patients and 45 non-diabetic patients with vascular calcification. The prevalence of vascular calcification in diabetic patients (47.1%) was higher than in non-diabetic patients (13.6%) ( p<0.001). In multivariate logistic regression, the main factors affecting vascular calcification in non-diabetic patients were advanced age, longer duration of haemodialysis, increased phosphate concentrations, male gender, and lower predialysis diastolic pressure. In diabetic patients, predictors for vascular calcification were higher values of HbA(1C) and longer duration of haemodialysis. In diabetic patients, a 1% increase in HbA(1C) increased the risk of calcification by 2.1-fold (95% CI 1.282-3.575, p=0.0029). CONCLUSION/INTERPRETATION: We have shown that poor glycaemic control, rather than calcium and phosphate concentrations, is a predictor of peripheral vascular calcification in diabetic patients on haemodialysis. This study emphasizes that glycaemic control remains critical even in diabetic patients with end-stage renal disease.     

Hyperglycaemia increases dipeptidyl peptidase IV activity in diabetes mellitus

Aims/hypotheses Chronic hyperglycaemia increases dipeptidyl peptidase IV (DPP-IV) activity in endothelial cells in vitro. The present study was designed to assess the effect of high glucose on circulating DPP-IV activity in patients with type 1 and type 2 diabetes.Methods Plasma DPP-IV activity was measured in 29 patients with type 1 diabetes and 29 age-, sex- and BMI-matched control subjects. We also assessed DPP-IV activity in 31 type 2 diabetic patients with HbA₁c >8.5% and in plasma from matched groups of 31 newly diagnosed diabetic subjects with HbA₁c <7.5%, 31 subjects with IGT and 62 subjects with NGT. In a further sample of 66 type 2 diabetic patients, a longitudinal study was also performed to evaluate variations in DPP-IV activity and HbA₁c over 3 months.Results DPP-IV activity in type 1 diabetic patients was not significantly different from that in control subjects; however, a significant correlation between DPP-IV and HbA₁c was observed in diabetic subjects (r=0.47; p<0.01). Type 2 diabetic patients with HbA₁c >8.5% showed significantly (p<0.05) higher DPP-IV activity (mean±SD 27.7±7.1 U/l) than newly diagnosed diabetic patients and subjects with IGT (22.1±6.0 and 18.8±8.8 U/l, respectively). Variations in DPP-IV activity over 3 months in type 2 diabetic patients showed a significant positive correlation with variations in HbA₁c (r=0.26; p<0.05).Conclusions/interpretation Chronic hyperglycaemia induces a significant increase in DPP-IV activity in type 1 and type 2 diabetes. This phenomenon could contribute to the reduction in circulating active glucagon-like peptide-1 and to the consequent postprandial hyperglycaemia in type 2 diabetic patients with poor metabolic control.     

The effect of long-term glycaemic control on serum lipoprotein(a) levels in patients with Type 2 diabetes mellitus.

AIMS: To examine whether long-term glycaemic control affects lipoprotein(a) (Lp(a)) levels in patients with Type 2 diabetes mellitus. METHODS: Eighty-nine Type 2 diabetic patients (38 men, 51 women) were recruited from the diabetes clinic. Based on HbA1c concentrations at baseline, patients were divided into two groups: those with HbA1c < 8.0% (n =45) and those with HbA1c > or = 8.0% (n=44). Comparisons of Lp(a) levels were made between both groups. The effect of long-term glycaemic control on Lp(a) levels was investigated in a subgroup of 20 patients, selected from those with baseline HbA1c > or = 8%. All these patients were treated with a goal of HbA1c <7%. RESULTS: Lp(a) levels were not significantly different between those with HbA1c< 8.0% and those with HbA1c, > or = 8.0%. No correlation between Lp(a) and HbA1c or fasting blood glucose levels was noted in diabetic patients as a whole. After 2 years of intensive glycaemic control, all patients exhibited remarkable improvement of therapy: their average HbA1c levels were 6.5 +/- 0.7%, being < 7% in 70% of patients. However, no change in Lp(a) levels were observed after 2 years (19.5 +/- 14.8-21.4 +/- 13.4 mg/dl, P = 0.390). CONCLUSION: These results indicate that improvement of glycaemic control does not affect serum Lp(a) levels in patients with Type 2 diabetes mellitus.     

Early parasympathetic neuropathy associated with elevated fasting plasma C-peptide concentrations and late parasympathetic neuropathy with hyperglycaemia and other microvascular complications.

AIMS: To examine the relationship between parasympathetic neuropathy, hyperinsulinaemia, glycaemic control (HbA(1c)), and future diabetic complications. METHODS: We assessed parasympathetic nerve function [expiration/inspiration (E/I) ratio], glomerular filtration rate (GFR), glycaemic control (HbA(1c)), fasting plasma (f-p-) C-peptide in 82 Type 2 diabetic patients (age 61 +/- 1 years) 5 and 12-15 years after diagnosis. Diabetic retinopathy was assessed 15 years after diagnosis. RESULTS: High HbA(1c) values in the first study were associated with retinopathy (with 8.6 +/- 2.0 vs. without retinopathy 6.2 +/- 1.9%; P < 0.0001) and disturbed parasympathetic nerve function (low E/I ratio; r(s) = -0.41; P = 0.0061) in the second study, as well as with deteriorations in GFR between the first and second study (r(s) = 0.62; P < 0.0001). Patients with parasympathetic neuropathy in the first study had significantly higher f-p-C-peptide concentrations than those without 3 years (1.20 +/- 0.43 vs. 0.86 +/- 0.40 nmol/l; P = 0.0015) and 5 years (1.20 +/- 0.44 vs. 0.82 +/- 0.33 nmol/l; P < 0.0001), but not 15 years after diagnosis. CONCLUSION: High HbA(1c) values 5 years after diagnosis of Type 2 diabetes were associated with retinopathy, disturbed parasympathetic nerve function, and deterioration in GFR 7-10 years later. Parasympathetic neuropathy 5 years after diagnosis was associated with high C-peptide concentrations. Parasympathetic nerve function has to be considered when beta-cell function is evaluated. Hyperglycaemia is an important factor for the development of complications in Type 2 diabetes.     

Ca(2+)-Mg(2+)-ATPase activity and ionized calcium in Type 2 diabetic patients with neuropathy

Ca(2+)-Mg(2+)-ATPase is an important regulator of intracellular calcium concentration and therefore, of erythrocyte deformability. We have investigated the possible relationship between Ca(2+)-Mg(2+)-ATPase activity (ATPase) and ionized calcium (Ca(2+)), in diabetic patients with peripheral neuropathy. A total of 104 Type 2 diabetic patients (57 neuropathic and 47 non-neuropathic) and 25 non-diabetic subjects were studied. After an overnight fast, blood was taken for Ca(2+)-Mg(2+)-ATPase activity, Ca(2+), Mg(2+), PTH and HbA(1c). The neuropathy study group had significantly lower levels of ATPase, 6.6 (95% CI, 5.6-7.7) nmol/mg/min compared to controls 7. 1 (6.2-8.3) nmol/mg/min, P<0.001 and to diabetic patients without neuropathy 7.0 (6.0-8.1) nmol/mg/min, P<0.001. The study group had also lower levels of Ca(2+) (0.89+/-0.18 mmol/l vs. control 1.08+/-0. 24 mmol/l, P<0.01 and non-neuropathic 0.98+/-0.27 mmol/l, P<0.05) and Mg(2+) (0.73+/-0.13 mmol/l vs. control 0.81+/-0.14 mmol/l, P<0. 05), despite similar PTH levels. In diabetic subjects, no correlation was found between ATPase or Ca(2+) with glucose, HbA(1c), age or duration of diabetes. We conclude that in patients with diabetic neuropathy there are abnormalities of Ca(2+)-Mg(2+)-ATPase activity and Ca(2+). This provides further support for the role of microangiopathy in the pathogenesis of neuropathy.     

Insufficient adaptation of hypoglycaemic threshold for cognitive impairment in tightly controlled type 1 diabetes

It is well known that hypoglycaemic thresholds for hormones and symptoms occur at lower plasma glucose levels in patients with strict glycaemic control. However, whether the threshold for cognitive impairment also shifts is still an unresolved question. We studied 19 type 1 diabetic patients, including 8 with hypoglycaemia unawareness, aged 37.0 +/- 7.4 y.r., with diabetes duration 15.2 +/- 10.7 yr, and HbA1c 7.6 +/- 1.1%. Hypoglycaemic thresholds for hormones, symptoms, awareness and cognitive function using the 4-choice reaction time test (4RT), were measured every 30 min during a 150 min stepped 4.4 to 2.2 mM hypoglycaemic hyperinsulinemic clamp. We found that 4RT- accuracy deteriorated earlier than 4RT-time (3.2 and 2.7 mM, respectively, p<0.01), and that both correlated poorly with HbA1C before and after adjustment for age and diabetes duration (r=0.11, and 0.18, respectively). On the opposite, adrenaline, autonomic and neuroglycopenic symptoms, and awareness significantly correlated with HbA1c values (r=0.56, 0.70, 0.61, and 0.63, after adjustment, respectively). Furthermore, after allocating the patients into two subgroups according to HbA1c values (<8% n=12, and >=8% n=7), we found that, as opposed to other thresholds, accuracy and 4RT-time were minimally and not significantly influenced by glycaemic control, therefore exhibiting the smaller glucose thresholds shifts (- 0.2 and - 0.5 mM for accuracy and time, respectively, vs. 0.6 -0.8 for other thresholds). In conclusion: 1) the hypoglycaemic thresholds for cognitive dysfunction shift with strict glycaemic control, but not significantly and less than other thresholds, 2) as opposed to other reports, accuracy deteriorates earlier than speed during the 4RT test, and 3) these "maladapted" reactions may contribute to the higher risk for severe hypoglycaemia in subjects with tight glycaemic control.     

Similar elimination rates of glucagon-like peptide-1 in obese type 2 diabetic patients and healthy subjects

We have previously shown that type 2 diabetic patients have decreased plasma concentrations of glucagon-like peptide 1 (GLP-1) compared with healthy subjects after ingestion of a standard mixed meal. This decrease could be caused by differences in the metabolism of GLP-1. The objective of this study was to examine the pharmacokinetics of GLP-1 in healthy subjects and type 2 diabetic patients after iv bolus doses ranging from 2.5-25 nmol/subject. Bolus injections iv of 2.5, 5, 15, and 25 nmol of GLP-1 and a meal test were performed in six type 2 diabetic patients [age, mean (range): 56 (48-67) yr; body mass index: 31.2 (27.0-37.7) kg/m(2); fasting plasma glucose: 11.9 (8.3-14.3) mmol/liter; hemoglobin A(1C): 9.6 (7.0-12.5)%]. For comparison, six matched healthy subjects were examined. Peak plasma GLP-1 concentrations increased linearly with increasing doses of GLP-1 and were similar for type 2 diabetic patients and healthy subjects. The peak concentrations of total GLP-1 (C-terminal) after 2.5, 5, 15, and 25 nmol of GLP-1 were 357 +/- 56, 647 +/- 141, 1978 +/- 276, 3435 +/- 331 pmol/liter in the type 2 diabetic patients and 315 +/- 37, 676 +/- 64, 1848 +/- 146, 3168 +/- 358 pmol/liter, respectively, in the healthy subjects (not statistically significant). Peak concentrations of the intact GLP-1 peptide (N-terminal) were: 69 +/- 17, 156 +/- 44, 703 +/- 77, and 1070 +/- 117 pmol/liter in the type 2 diabetic patients and 75 +/- 14, 160 +/- 40, 664 +/- 79, 974 +/- 87 in the healthy subjects (not statistically significant). GLP-1 was eliminated rapidly with clearances of intact GLP-1 after 2.5, 5, 15, and 25 nmol of GLP-1 amounting to: 9.0 +/- 5.0, 8.1 +/- 6.0, 4.0 +/- 1.0, 4.0 +/- 1.0 liter/min in type 2 diabetic patients and 8.4 +/- 4.2, 7.6 +/- 4.5, 5.0 +/- 2.0, 5.0 +/- 1.0 liter/min in healthy subjects. The volume of distribution ranged from 9-26 liters per subject. No significant differences were found between healthy subjects and type 2 diabetic subjects. We conclude that elimination of GLP-1 is the same in obese type 2 diabetic patients and matched healthy subjects. The impaired incretin response seen after ingestion of a standard breakfast meal must therefore be caused by a decreased secretion of GLP-1 in type 2 diabetic patients.     

Synergistic effect of polymorphisms in uncoupling protein 1 and beta3-adrenergic receptor genes on long-term body weight change in Finnish type 2 diabetic and non-diabetic control subjects

OBJECTIVE: To investigate the independent and combined effects of the Trp64Arg polymorphism of the beta3-adrenergic receptor (beta3AR) gene and the (-3826) A-->G polymorphism of the uncoupling protein 1 (UCP1) gene on body weight change in type 2 diabetic and non-diabetic control subjects during a 10y follow-up study. DESIGN: Controlled 10y follow-up study with baseline, 5 and 10y examinations. SUBJECTS: 70 newly diagnosed, middle-aged type 2 diabetic patients and 123 non-diabetic control subjects from eastern Finland. MEASUREMENTS: Anthropometric measurements, blood pressure, oral glucose tolerance test, plasma insulin, plasma C-peptide and HbA1c. Genotypes by polymerase chain reaction followed by enzymatic digestion. RESULTS: No significant differences were found in the frequencies of the two polymorphisms between diabetic and control subjects. The polymorphisms were not cross-sectionally or longitudinally associated with body weight or BMI in diabetic or control subjects. When the diabetic and control subjects were analysed together, the change in the mean body weight was significantly greater among the subjects with both polymorphisms (n = 11) than among those with no polymorphisms (n = 103; change in weight 6.5 +/- 2.5% vs -0.2 +/- 0.8%, P=0.036, and change in Body Mass Index 8.5 +/- 2.6% vs 2.0 +/- 0.8%, P= 0.060, mean +/- s.e.m.). CONCLUSIONS: The simultaneous existence of the two polymorphisms was associated with a tendency to gain weight suggesting a synergistic effect of these polymorphisms on body weight gain.     

Relative hypoleptinemia in patients with type 1 and type 2 diabetes mellitus

OBJECTIVE: To determine the relation between plasma leptin concentrations and metabolic control in human diabetes mellitus. DESIGN AND SUBJECTS: Cross sectional study consisting of 156 patients with diabetes mellitus type 1 (n=42), type 2 (n=114), and non-diabetic subjects (n=74). RESULTS: Plasma leptin concentrations were lower (P<0.05) in type 1 (8.3+/-1.7 ng/ml) and type 2 diabetic (14.9+/-1.8 ng/ml) than in non-diabetic humans (18.3+/-1.9 ng/ml). Only female type 1 and type 2 diabetic subjects also had decreased leptin/BMI ratios (P<0.05 vs non-diabetic females). The log rank test identified age-adjusted correlation of plasma leptin concentration with sex (P<0.0004) and body mass index (P<0.0218), but not with glycosylated haemoglobin A1c (P>0.5) in all groups. Plasma leptin was correlated with age (P<0.0058) and serum triglycerides (P<0.0199) in type 1 diabetic patients, and with serum cholesterol (P<0.0059) and LDL (P<0.0013) in type 2 diabetic patients. CONCLUSIONS: Defective leptin production and/or secretion might be present independently of metabolic control in female patients with type 1 or type 2 diabetes mellitus.     

No reactive hypoglycaemia in Type 2 diabetic patients after subcutaneous administration of GLP-1 and intravenous glucose.

AIMS: It has previously been shown that intravenous and subcutaneous administration of glucagon-like peptide (GLP)-1 concomitant with intravenous glucose results in reactive hypoglycaemia in healthy subjects. Since GLP-1 is also effective in Type 2 diabetic patients and is presently being evaluated as a therapeutic agent in this disease, it is important to investigate whether GLP-1 can cause hypoglycaemia in such patients. METHODS: Eight Type 2 diabetic patients (age 54 (49-67) years; body mass index 31 (27-38) kg/m2; HbA1c 9.4 (7.0-12.5)%) and seven matched non-diabetic subjects (HbA1c 5.5 (5.2-5.8)%, fasting plasma glucose 5.4 (5.0-5.7) mmol/l) were given a subcutaneous injection of 1.5 nmol GLP-1/kg body weight (maximally tolerated dose), and 15 min later, plasma glucose (PG) was raised to 15 mmol/l with an intravenous glucose bolus. RESULTS: Hypoglycaemia with a PG at or below 2.5 mmol/l was seen in five of the seven healthy subjects after 60-70 min, but PG spontaneously increased again, reaching 3.7 (3.3-4.0) mmol/l at 90 min. In the patients, PG fell slowly and stabilized at 8.6 (4.2-12.1) mmol/l after 80 min. In both groups, glucagon levels initially decreased, but later increased, exceeding basal levels in healthy subjects, in spite of persistent, high concentrations of GLP-1 (P < 0.02). CONCLUSIONS: Subcutaneous GLP-1 plus intravenous glucose induced reactive hypoglycaemia in healthy subjects, but not in Type 2 diabetic patients. Therefore, a GLP-1-based therapy would not be expected to be associated with an increased risk of hypoglycaemia in Type 2 diabetes mellitus.     

Determinants of glycaemic control in type 1 diabetes during intensified therapy with multiple daily insulin injections or continuous subcutaneous insulin infusion: importance of blood glucose variability

BACKGROUND AND METHODS: We investigated the factors that determine the best glycaemic control on multiple daily insulin (MDI) injections and continuous subcutaneous insulin infusion (CSII), and the hypothesis that blood glucose variability is a major determinant of control and that the resultant HbA(1c) on MDI correlates with the improvement achieved by CSII. We studied 30 type 1 diabetic subjects already receiving MDI. Renewed attempts to improve control on MDI were made for a median of five months, and then the subjects were switched to CSII. The variability of within-day and between-day blood glucose concentrations was calculated from blood glucose self-monitoring data. RESULTS: HbA(1c) during MDI varied from 5.7 to 11.7% (mean +/- SD, 8.5 +/- 1.4%). Within- and between-day blood glucose variability correlated with HbA(1c) on MDI (r = 0.59, p < 0.001; r = 0.48, p < 0.03). Within-day variability remained an independent predictor of HbA(1c) on MDI. Mean HbA(1c) improved with CSII (to 7.3 +/- 0.9%, p < 0.001), but reduction in HbA(1c) was variable and was related to the HbA(1c) on MDI (r = 0.79, p < 0.001) and within-day variability (r = 0.56, p < 0.01). Similar results were observed for subjects treated only with glargine-based MDI. CONCLUSIONS: The best glycaemic control achievable on MDI is related to blood glucose variability-those with the largest swings in blood glucose retaining the highest HbA(1c). The improvement in control achieved by CSII is related to HbA(1c) and blood glucose variability on MDI. Pump therapy is most effective in those worst controlled on MDI.     

Factors affecting perinatal morbidity and mortality in pregnancies complicated by diabetes mellitus in Sudan

To investigate the influence of obstetric factors and indices of maternal metabolic control on perinatal morbidity and mortality, 88 diabetic pregnant Sudanese women (type 1, n=38; type 2, n=31; gestational diabetes, n=19) and 50 non-diabetic pregnant control women were studied. The mean fasting blood glucose was 11.1+/-2.8 mmol/l and the mean HbA(1c) at booking interview was 8.8+/-2.1% in the diabetic women. Pregnancy complications such as Caesarean sections, urinary tract infections, pregnancy-induced hypertension and intrauterine foetal death were higher among diabetic compared with control women (P<0.0001) and varied with the type of diabetes. Infants of diabetic mothers had a higher incidence of neonatal complications than those of non-diabetic women (54.4% vs. 20.0%; P<0.0001). Infants without complications and who were born to diabetic mothers had better Apgar scores at 5 min (9.8+/-0.5 vs. 8.9+/-1.6; P<0.01) and lower cord C-peptide when compared to infants with complications (P<0.05). In conclusion, the prevalence of maternal and neonatal complications among Sudanese diabetic women and their infants is high. Maternal hyperglycaemia is an important factor affecting maternal wellbeing and neonatal morbidity and mortality.     

Significant bacteriuria in outpatient diabetic and non-diabetic persons.

AIMS: The prevalence of significant bacteriuria (SB) in diabetes mellitus has not been clearly established. Having previously investigated SB frequency in inpatient diabetic women, we now screened for SB (both asymptomatic and symptomatic forms) in outpatients. METHODS: We examined 511 consecutive outpatients with Type 1 (T1D) or Type 2 diabetes (T2D), and 98 non-diabetic subjects. At least one uncontaminated midstream urine sample was available from 602 subjects: 64 T1D (37 female, age 49 +/- 13 years, diabetes duration 23 +/- 15 years), 441 T2D (212 female, 66 +/- 10 years, 12 +/- 10 years), and 97 healthy control subjects (39 female, 57 +/- 12 years). On the same day, we determined: blood cell count, fasting plasma glucose (FPG), glycated haemoglobin (HbA(1c)), plasma creatinine, urinary creatinine, and urinary albumin excretion (UAE; microg/mg urinary creatinine). RESULTS: The rate of SB was 14.1% in T1D, 9.3% in T2D and 6.2% in control subjects (P = NS). The 50 diabetic patients with SB differed from the 455 diabetic patients without SB in gender (43 male vs. 206 female, P < 0.001), FPG (10.2 +/- 3.6 vs. 9.2 +/- 2.9 mmol/l, P < 0.05), HbA(1c) (7.8 +/- 1.1 vs. 7.5 +/- 1.3%, P < 0.05), and UAE (median 15.6 vs. 7.6 microg/mg, P < 0.01). Eleven diabetic patients with SB had symptoms (vs. 48 without SB, P < 0.05); UAE levels were higher in the 39 asymptomatic diabetic patients with SB than in the 11 symptomatic patients. CONCLUSIONS: The prevalence of SB is similar in outpatient diabetic individuals and in non-diabetic subjects. The main risk factors for SB in diabetic patients were female gender and UAE. The likelihood of asymptomatic SB increased with UAE levels, i.e. with the presence of established microangiopathy. Poor glycaemic control is associated with bacteriuria, either as a cause or consequence of bacteriuria.     

Effect of glycaemic control on the vascular nitric oxide system in patients with type 1 diabetes

OBJECTIVE: The mechanisms underlying the relationship between the vascular complications of diabetes and the glycaemic control are not well understood. We tested whether glycaemic control influences the functioning of the nitric oxide system in type 1 diabetic patients and the role for oxidative stress. METHODS: The changes in the forearm blood flow after the infusion in the brachial artery of NG-monomethyl-l-arginine, methacholine, methacholine plus superoxide dismutase, and nitroprusside were evaluated using strain gauge plethysmography in 14 healthy subjects and 24 patients with type 1 diabetes (12 with HbA(1c) < 7.5%; 12 with HbA(1c) > or = 7.5%). After adjusting insulin treatment, the vascular studies were repeated in the initially poorly controlled patients (HbA(1c) > or = 7.5%). RESULTS: Compared with healthy people, impaired vascular responses to NG-monomethyl-l-arginine (P = 0.0001), methacholine (P = 0.007) and nitroprusside (P = 0.0015) were found in the patients with type 1 diabetes and a poor glycaemic control (HbA(1c) >/= 7.5%), but not in subjects with good control (HbA(1c) < 7.5%). Superoxide dismutase improved the responses to methacholine only in those patients with poor control (P = 0.0037). After the adjustment of the insulin treatment in poorly-controlled patients, the responses improved and the effect of superoxide dismutase disappeared only in the patients that achieved good control (n = 9), but not in those who remained poorly-controlled (n = 3). CONCLUSIONS: In patients with diabetes type 1, glycaemic control determines the functioning of the NO system by a reversible mechanism involving superoxide anions. This finding provides an explanation of the relationship between glycaemic control and vascular complications in diabetes.     

Comparison of glycated albumin (GA) and glycated hemoglobin (HbA1c) in type 2 diabetic patients: usefulness of GA for evaluation of short-term changes in glycemic control

We studied the cross-sectional relationship between GA and HbA1c in 142 type 2 diabetic patients who had an HbA1c level < 7.5% for at least one year without fluctuation by more than 0.5%. We also followed the changes of GA and HbA1c in 18 type 2 diabetic patients for 16 weeks as they progressed from untreated severe hyperglycemia (HbA1c > or = 9.0%) to good glycemic control (HbA1c < or = 6.5%) by intensive insulin treatment. The annual mean levels of GA and HbA1c in the stably controlled patients showed a weak, but significant, correlation (r = 0.23, p<0.001) in the 142 diabetic patients. However, the GA/HbA1c ratio ranged widely from 2.0 to 4.0 showing a normal distribution (2.9 +/- 0.34, M +/- SE), although patients with conditions affecting albumin turnover or RBC lifespan were excluded from the study. The GA/HbA1c ratio was significantly higher when patients were in hyperglycemic than when glycemic control was good (3.5 +/- 0.15 vs. 2.9 +/- 0.07, M +/- SE, p<0.01). GA decreased more rapidly than HbA1c during intensive insulin therapy, but the percent reduction of HbA1c eventually corresponded with that of GA by 16 weeks after the start of treatment. These results demonstrate that, although unknown influences on GA or HbA1c may exist, GA may be a useful marker for monitoring short-term variations of glycemic control during treatment of diabetic patients.     

Serum adiponectin concentrations are not related to glycosylated hemoglobin levels (HbA1c) in obese diabetic and non-diabetic caucasians.

Although circulating adiponectin has been inversely correlated with obesity, type 2 diabetes and serum glycosylated hemoglobin (HbA1c) in humans, contradictory reports on that subject exist. In this study, serum concentrations of adiponectin in obese non-diabetic and diabetic humans were measured to examine whether they were associated with levels of HbA1c. The WHO definitions of obesity and diabetes were used. One hundred and five obese euglycemic subjects and 49 obese diabetics (aged 51+/-6.9, and 52+/-6.7 years, respectively) were studied. Their BMI, HbA1c and % of body fat were measured. Adiponectin was determined by an enzyme-linked immunosorbent assay. Although the serum adiponectin concentrations differed between diabetics and non-diabetics ( P<0.01), they were not correlated with HbA1c (r=-0.0814; P=0.5823, and r=-0.1861; P=0.1099, for diabetics and non-diabetics, respectively). Both diabetics and non-diabetics were segregated into tertiles according to their HbA1c levels. Plasma adiponectin did not differ significantly between the high (H), intermediate (I), and low (L) HbA1c tertiles. CONCLUSION: Concentrations of adiponectin were not correlated with levels of glycosylated hemoglobin in the diabetic and non-diabetic subjects examined.     

Inhibition of dipeptidyl peptidase IV activity by oral metformin in Type 2 diabetes.

AIMS: Glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) are important insulinotropic hormones that enhance the insulin secretory response to feeding. Their potential for treating Type 2 diabetes is limited by short biological half-life owing to degradation by dipeptidyl peptidase IV (DPP IV). We investigated the acute effects of metformin on DPP IV activity in Type 2 diabetes to elucidate inhibition of DPP IV as a possible mechanism of action. METHODS: Eight fasting subjects with Type 2 diabetes (5M/3F, age 53.1+/-4.2 years, BMI 36.8+/-1.8 kg/m2, glucose 8.9+/-1.2 mmol/l, HbA1c 7.8+/-0.6%) received placebo or metformin 1 g orally 1 week apart in a random, crossover design. RESULTS: Following metformin, DPP IV activity was suppressed compared with placebo (AUC0-6 h 3230+/-373 vs. 5764+/-504 nmol ml/l, respectively, P=0.001). Circulating glucose, insulin and total GLP-1 were unchanged. Metformin also concentration-dependently inhibited endogenous DPP IV activity in vitro in plasma from Type 2 diabetic subjects. CONCLUSION: Oral metformin effectively inhibits DPP IV activity in Type 2 diabetic patients, suggesting that the drug may have potential for future combination therapy with incretin hormones.