New variants in the glycogen synthase gene (Gln71His, Met416Val) in patients with NIDDM from eastern Finland

Summary Impaired glycogen synthesis after insulin stimulation accounts for most of the insulin resistance in patients with non-insulin-dependent diabetes mellitus (NIDDM). The glycogen synthase gene (GYS1), which encodes the rate-limiting enzyme for glycogen synthesis, is a promising candidate gene for NIDDM. Therefore, we screened all 16 exons of this gene by single-strand conformation polymorphism analysis in 40 patients with NIDDM (age 67 ± 2 years, body mass index 28.2 ± 0.6 kg/m²) from Taipalsaari, eastern Finland. The Gly464Ser variant (exon 11) and a silent polymorphism TTC342TTT (exon 7) have been reported previously. In addition, we found a new variant Gln71His (exon 2) and a new amino acid polymorphism Met416Val (exon 10). An additional sample of 65 patients with NIDDM and 82 normoglycaemic men (age 54 ± 1 years, body mass index 26.3 ± 1.4 kg/m²) were screened. The allele frequency of the TTC342TTT silent substitution was 0.29 in both NIDDM and normoglycaemic subjects. The Gln71His and Gly464Ser variants were found in 1 (1 %) and 3 (3 %) subjects, respectively, of the 105 NIDDM patients and in none of the 82 normoglycaemic men. The Met416Val polymorphism was found in 16 (15 %) of the 105 NIDDM patients and in 14 (17 %) of the 82 control subjects (all heterozygous). The Met416Val polymorphism was not associated with insulin resistance in two groups of normoglycaemic subjects. In conclusion, the new Gln71His and Met416Val substitutions and other variants of the glycogen synthase gene are unlikely to make a major contribution to insulin resistance and NIDDM in diabetic patients from eastern Finland. [Diabetologia (1997) 40: 1313–1319] Received: 17 April 1997 and in revised form: 30 June 1997     

Non-invasive tracing of liver intermediary metabolism in normal subjects and in moderately hyperglycaemic NIDDM subjects. Evidence against increased gluconeogenesis and hepatic fatty acid oxidation in NIDDM

Summary To test whether gluconeogenesis is increased in non-insulin-dependent diabetic (NIDDM) patients we infused (post-absorptive state) healthy subjects and NIDDM patients with [6,6-²H₂]glucose (150 min) and [3-¹³C]lactate (6 h). Liver glutamine was sampled with phenylacetate and its labelling pattern determined (mass spectrometry) after purification of the glutamine moiety of urinary phenylacetylglutamine. After correction for ¹³CO₂ re-incorporation (control test with NaH¹³CO₃ infusion) this pattern was used to calculate the dilution factor (F) in the hepatic oxaloacetate pool and fluxes through liver Krebs cycle. NIDDM patients had increased lactate turnover rates (16.18 ± 0.92 vs 12.14 ± 0.60 μmol · kg⁻¹· min⁻¹, p < 0.01) and a moderate rise in glucose production (EGP) (15.39 ± 0.87 vs 12.52 ± 0.28 μmol · kg⁻¹· min⁻¹, p = 0.047). Uncorrected contributions of gluconeogenesis to EGP were 31 ± 3 % (control subjects) and 17 ± 2 % (NIDDM patients). F was comparable (1.34 ± 0.02 and 1.39 ± 0.09, respectively) and the corrected percent and absolute contributions of gluconeogenesis were not increased in NIDDM (25 ± 3 % and 3.8 ± 0.5 μmol · kg⁻¹· min⁻¹) compared to control subjects (41 ± 3 % and 5.1 ± 0.4 μmol · kg⁻¹· min⁻¹). The calculated pyruvate carboxylase over pyruvate dehydrogenase activity ratio was comparable (12.1 ± 2.6 vs 11.2 ± 1.4). Lastly hepatic fatty oxidation, as estimated by the model, was not increased in NIDDM (1.8 ± 0.4 vs 1.6 ± 0.1 μmol · kg⁻¹· min⁻¹). In conclusion, in the patients studied we found no evidence of increased hepatic fatty oxidation, or, despite the increased lactate turnover rate, an increased gluconeogenesis. [Diabetologia (1998) 41: 212–220] Received: 4 July 1997 and in revised form: 16 September 1997     

Simple tandem repeat DNA polymorphism in the human glycogen synthase gene is associated with NIDDM in Japanese subjects

Summary We investigated the possible association between alleles of a simple tandem repeat DNA polymorphism in the human glycogen synthase gene and non-obese non-insulin-dependent diabetes (NIDDM) in Japanese subjects. Nine alleles (−4G, −3G, −2G, −1G, 0G, 1G, 2G, 3G, and 4G) were identified in the study group of 164 patients with NIDDM and 115 non-diabetic subjects. The overall frequency distribution of the glycogen synthase gene alleles was significantly different between the two groups (p =0.0316). The 2G allele was found more frequently in patients with NIDDM than in non-diabetic subjects (17.7 % vs 8.7 %, p =0.0016). These results suggest that the 2G allele could be a genetic marker of NIDDM in Japanese subjects. [Diabetologia (1994) 37: 536–539] Received: 13 November 1993 and in revised form: 3 January 1994     

High density lipoprotein apolipoprotein AI kinetics in NIDDM: a stable isotope study

Summary High density lipoprotein (HDL) kinetics were studied by infusing [5,5,5-²H₃]-leucine in five subjects with normal glucose tolerance and eight patients with non-insulin-dependent diabetes mellitus (NIDDM) with poor metabolic control (HbA_{1 c} = 8.16 ± 1.93 %) (mean ± SD). HDL were modelled as a single compartment since no kinetic differences were observed between HDL2 and HDL3 subclasses. Plasma apolipoprotein AI (apo AI) concentration was significantly lower in NIDDM patients (96.1 ± 12.1 vs 124.4 ± 13.1 mg · dl⁻¹, p < 0.01). HDL composition was altered in NIDDM, as an increase in HDL-triglyceride and a decrease in HDL-cholesterol, negatively correlated (r = −0.780, p < 0.01). The mean fractional catabolic rate (FCR) of apo AI-HDL was significantly higher (0.39 ± 0.16 vs 0.21 ± 0.06 d⁻¹, p < 0.05) while the apo AI-HDL absolute production rate was not significantly greater (13.6 ± 5.1 vs 12.0 ± 4.2 mg · kg⁻¹· d⁻¹) in diabetic patients compared to normal subjects. There were significant correlations between apo AI-HDL FCR and plasma apo AI concentration (r = −0.580, p < 0.05), plasma triglycerides (r = 0.839, p < 0.001) or HDL-triglyceride levels (r = 0.597, p < 0.05). No correlation was observed between apo AI-HDL FCR and HbA_{1 c} or HDL-cholesterol level. These data support the view that the decrease in plasma apo AI level in patients with NIDDM is due to an increase of apo AI-HDL FCR, which may itself be related to changes in HDL composition. [Diabetologia (1997) 40: 578–583] Received: 15 October 1996 and in revised form: 17 January 1997     

Detection of variants in the mitochondrial glycerophosphate dehydrogenase gene in Japanese NIDDM patients

Summary Mitochondrial FAD-linked glycerophosphate dehydrogenase (mGPDH) is thought to be an important factor for glucose sensing in pancreatic beta cells. To evaluate the significance of the mGPDH gene in the development of non-insulin-dependent diabetes mellitus (NIDDM), we set up primers and conditions for polymerase chain reaction (PCR) amplification of the coding exons and flanking regions. Screening of 100 Japanese NIDDM patients for mutations using the PCR-single strand conformation polymorphism (SSCP) method revealed four variants (ACA:Thr243-ACG:Thr243, CAT:His264-CGT:Arg264, GCA:Ala305-GCC:Ala305, GCA:Ala 306-TCA:Ser306). The His264-Arg264 variant was found in 36 patients, while the other variants were found in only one patient each. Neither the genotypic (χ² = 3.15, p = 0.21) nor the allelic (χ² = 2.27, p = 0.13) frequency of the His264-Arg264 mutation differed between 253 Japanese NIDDM patients and 157 non-diabetic subjects. In addition, in NIDDM patients, neither the treatment modality nor body mass index differed between those with and without this mutation. These results suggest that inherited defects at this locus do not make a major contribution to genetic susceptibility to NIDDM in the Japanese population. [Diabetologia (1997) 40: 339–343] Received: 14 August 1996 and in revised form: 5 December 1996     

Insulin resistance characterizes glucose uptake in skeletal muscle but not in the heart in NIDDM

Summary Skeletal muscle insulin resistance and coronary heart disease (CHD) often precede non-insulin-dependent diabetes mellitus (NIDDM). A recent study showed the myocardium of patients with CHD to be insulin resistant, independent of blood flow. We determined whether myocardial insulin resistance is a feature of NIDDM patients with no CHD. Skeletal muscle and myocardial glucose uptake were determined in 10 patients with NIDDM and 9 age- and weight-matched normal men of similar age and body mass index men using [¹⁸F]-2-fluoro-2-deoxy-d-glucose and positron emission tomography under normoglycaemic hyperinsulinaemic conditions. Whole body glucose uptake, as determined by the euglycaemic clamp technique, was significantly lower in the patients with NIDDM (35 ± 3 μmol/kg body weight · min) than the normal subjects (45 ± 3 μmol/kg body weight · min, p < 0.02). Insulin-stimulated femoral muscle glucose uptake was significantly lower in the patients with NIDDM (71 ± 6 μmol/kg muscle · min) than in the normal subjects (96 ± 5 μmol/kg muscle · min, p < 0.01). Whole body glucose uptake was correlated with femoral muscle glucose uptake in the entire group (r = 0.76, p < 0.001), in patients with NIDDM and in normal subjects. Rates of insulin-stimulated myocardial glucose uptake were comparable between the patients with NIDDM (814 ± 76 μmol/kg muscle · min) and the normal subjects (731 ± 63 μmol/kg muscle · min, p > 0.4). Whole body or femoral muscle, and myocardial glucose uptake were not correlated in all subjects, patients with NIDDM or normal subjects. We conclude that insulin resistance of the myocardium is not a feature of uncomplicated NIDDM. [Diabetologia (1998) 41: 555-559] Received: 8 August 1997 and in revised form: 6 December 1997     

Glomerular hyperfiltration in microalbuminuric NIDDM patients

Summary Glomerular hyperfiltration and microalbuminuria are both regarded as risk factors for the development of diabetic nephropathy in insulin-dependent diabetic patients. Information on glomerular hyperfiltration is scarse in microalbuminuric non-insulin-dependent diabetic (NIDDM) patients. Therefore, we performed a cross-sectional study of glomerular filtration rate (single i. v. bolus injection of ⁵¹Cr-EDTA, plasma clearance for 4 h) in 158 microalbuminuric NIDDM patients compared to 39 normoalbuminuric NIDDM patients and 20 non-diabetic control subjects. The groups were well-matched with regard to sex, age and body mass index. The uncorrected (ml/min) and the adjusted (ml · min^–1· 1.73 m^–2) glomerular filtration rate were both clearly elevated in the microalbuminuric patients: 139 ± 29 and 117 ± 24 as compared to 115 ± 19 and 99 ± 15; 111 ± 23 and 98 ± 21 in normoalbuminuric NIDDM patients and control subjects, respectively (p < 0.001). The glomerular filtration rate (ml · min^–1· 1.73 m^–2) in NIDDM patients who had never received antihypertensive treatment was also clearly elevated in the microalbuminuric patients (n = 96): 119 ± 22 as compared to 100 ± 14 and 98 ± 21 in normoalbuminuric NIDDM patients (n = 27) and control subjects (n = 20), respectively (p < 0.001). Glomerular hyperfiltration (elevation above mean glomerular filtration rate plus 2 SD in normoalbuminuric NIDDM patients) was demonstrated in 37 (95 % confidence interval 30–45)% of the microalbuminuric patients. Multiple regression analysis revealed that HbA_{1 c}, 24-h urinary sodium excretion, age and known duration of diabetes were correlated with glomerular filtration rate in microalbuminuric NIDDM patients (r ² = 0.21, p < 0.01). Our cross-sectional study indicates that NIDDM patients at high risk of developing diabetic nephropathy are also characterized by an additional putative risk factor for progression, glomerular hyperfiltration. [Diabetologia (1996) 39: 1584–1589]     

Risk and mechanism of dexamethasone-induced deterioration of glucose tolerance in non-diabetic first-degree relatives of NIDDM patients

Summary We tested the hypothesis that glucose intolerance develops in genetically prone subjects when exogenous insulin resistance is induced by dexamethasone (dex) and investigated whether the steroid-induced glucose intolerance is due to impairment of beta-cell function alone and/or insulin resistance. Oral glucose tolerance (OGTT) and intravenous glucose tolerance tests with minimal model analysis were performed before and following 5 days of dex treatment (4 mg/day) in 20 relatives of non-insulin-dependent diabetic (NIDDM) patients and in 20 matched control subjects (age: 29.6 ± 1.7 vs 29.6 ± 1.6 years, BMI: 25.1 ± 1.0 vs 25.1 ± 0.9 kg/m²). Before dex, glucose tolerance was similar in both groups (2-h plasma glucose concentration (PG): 5.5 ± 0.2 [range: 3.2–7.0] vs 5.5 ± 0.2 [3.7–7.4] mmol/l). Although insulin sensitivity (Si) was significantly lower in the relatives before dex, insulin sensitivity was reduced to a similar level during dex in both the relatives and control subjects (0.30 ± 0.04 vs 0.34 ± 0.04 10^–4 min^–1 per pmol/l, NS). During dex, the variation in the OGTT 2-h PG was greater in the relatives (8.5 ± 0.7 [3.9–17.0] vs 7.5 ± 0.3 [5.7–9.8] mmol/l, F-test p < 0.05) which, by inspection of the data, was caused by seven relatives with a higher PG than the maximal value seen in the control subjects (9.8 mmol/l). These “hyperglycaemic” relatives had diminished first phase insulin secretion (?1) both before and during dex compared with the “normal” relatives and the control subjects (pre-dex ?1: 12.6 ± 3.6 vs 26.4 ± 4.2 and 24.6 ± 3.6 (p < 0.05), post-dex ?1: 22.2 ± 6.6 vs 48.0 ± 7.2 and 46.2 ± 6.6 respectively (p < 0.05) pmol · l^–1· min^–1 per mg/dl). However, Si was similar in “hyperglycaemic” and “normal” relatives before dex (0.65 ± 0.10 vs 0.54 ± 0.10 10−4 · min^–1 per pmol/l) and suppressed similarly during dex (0.30 ± 0.07 vs 0.30 ± 0.06 10−4 · min^–1 per pmol/l). Multiple regression analysis confirmed the unique importance of low pre-dex beta-cell function to subsequent development of high 2-h post-dex OGTT plasma glucose levels (R ² = 0.56). In conclusion, exogenous induced insulin resistance by dex will induce impaired or diabetic glucose tolerance in those genetic relatives of NIDDM patients who have impaired beta-cell function (retrospectively) prior to dex exposure. These subjects are therefore unable to enhance their beta-cell response in order to match the dex-induced insulin resistant state. [Diabetologia (1997) 40: 1439–1448] Received: 20 January 1997 and in final revised form: 17 July 1997     

Effect of the amino acid alanine on glucagon secretion in non-diabetic and type 1 diabetic subjects during hyperinsulinaemic euglycaemia,hypoglycaemia and post-hypoglycaemic hyperglycaemia

Aims/hypothesis The aim of our study was to establish whether the well-known defective or absent secretion of glucagon in type 1 diabetes in response to hypoglycaemia is selective or includes lack of responses to other stimuli, such as amino acids. Materials and methods Responses of glucagon to hypoglycaemia were measured in eight patients with type 1 diabetes and six non-diabetic subjects during hyperinsulinaemic (insulin infusion 0.5 mU kg⁻¹ min⁻¹) and eu-, hypo- and hyperglycaemic clamp studies (sequential steps of plasma glucose 5.0, 2.9, 5.0, 10 mmol/l). Subjects were studied on three randomised occasions with infusion of low- or high-dose alanine, or saline. Results With saline, glucagon increased in hypoglycaemia in non-diabetic subjects but not in diabetic subjects. Glucagon increased further with low-dose (181 ± 16 ng l⁻¹ min⁻¹) and high-dose alanine (238 ± 20 ng l⁻¹ min⁻¹) in non-diabetic subjects, but only with high-dose alanine in diabetic subjects (area under curve 112 ± 5 ng l⁻¹ min⁻¹). The alanine-induced glucagon increase in diabetic subjects paralleled the spontaneous glucagon response to hypoglycaemia in non-diabetic subjects not receiving alanine. The greater responses of glucagon to hypoglycaemia with alanine infusion were offset by recovery of eu- or hyperglycaemia. Conclusions/interpretation In type 1 diabetes, the usually deficient responses of glucagon to hypoglycaemia may improve after increasing the concentration of plasma amino acids. Amino acid-enhanced secretion of glucagon in response to hypoglycaemia remains under physiological control since it is regulated primarily by the ambient plasma glucose concentration. These findings might be relevant to improving counter-regulatory defences against insulin-induced hypoglycaemia in type 1 diabetes.     

Attenuated neutrophil respiratory burst following acute hypoglycaemia in diabetic patients and normal subjects

The effects of insulin-induced hypoglycaemia on the neutrophil respiratory burst were investigated in six patients with type 1 diabetes and six non-diabetic control subjects. Plasma glucose reached similar nadirs in control subjects (0.9±0.1 mmol l^–1; mean±SEM) and diabetic patients (1.2±0.2 mmol l^–1) (NS). The resting neutrophil respiratory burst was similar in control subjects (1.26±0.15 mV) and diabetic patients (1.03±0.18 mV) (NS). The neutrophil respiratory burst fell following hypoglycaemia in control subjects and diabetic patients to 0.38±0.05 mV (P<0.001) and 0.54±0.09 mV (P<0.05), respectively. This fall was significantly greater in control subjects (ANOVA; P<0.001). Resting neutrophil counts were not significantly different in control subjects (3.2±0.3×10⁹ l^–1) and diabetic patients (6.1±1.5×10⁹ l^–1). Following hypoglycaemia, neutrophil numbers increased in control subjects and diabetic patients to 11.5±1.4×10⁹ l^–1 (P<0.01) and 9.7±1.7×10⁹ l^–1 (P<0.05), respectively. This increase was significantly greater in control subjects (ANOVA; P<0.001). These results suggest that the neutrophil respiratory burst is suppressed in response to hypoglycaemia and that this phenomenon is more pronounced in non-diabetic subjects. Received: 28 March 1997 / Accepted in revised form: 31 July 1997     

Difference in the influence of maternal and paternal NIDDM on pancreatic beta-cell activity and blood lipids in normoglycaemic non-diabetic adult offspring

Summary The 75-g oral glucose tolerance test was performed in 38 normoglycaemic (World Health Organization criteria) non-diabetic volunteers, aged 31–40 years, of whom 20 had a non-insulin-dependent diabetic (NIDDM) mother and 18 had an NIDDM father. At the time of the study the offspring of NIDDM mothers had a somewhat higher body mass index (BMI) (males: 26.5 ± 1.0 (mean ± SEM), females: 27.5 ± 1.5 kg/m²) than the offspring of NIDDM fathers (males: 23.4 ± 0.9, females: 24.2 ± 1.2 kg/m²). There was no difference in the time-course of glycaemia; however the serum concentrations of immunoreactive insulin (IRI), C-peptide and proinsulin were significantly higher in offspring of NIDDM mothers than in offspring of NIDDM fathers: area under the curve (AUC) serum IRI: 0.928 ± 0.091 vs 0.757 ± 0.056 nmol · l^–1· h^–1, p = 0.019; serum C-peptide: 6.379 ± 0.450 vs 4.753 ± 0.242 nmol · l^–1· h^–1, p = 0.004; serum proinsulin: 172 ± 40 vs 51 ± 7 pmol · l^–1· h^–1, p = 0.008). Serum IRI correlated with BMI, but C-peptide and proinsulin did not, and after accounting for BMI by covariance analysis they remained significantly higher in offspring of NIDDM mothers. In this group serum proinsulin was significantly higher in male than in female offspring (AUC serum proinsulin: 289 ± 68 vs 77 ± 27 pmol · l^–1· h^–1, P = 0.015). Male offspring of NIDDM mothers also had significantly higher serum triglyceride levels than females of the same group and than offspring of NIDDM fathers. The offspring (male and female) of NIDDM mothers had slightly lower serum apolipoprotein A-I levels than the offspring of NIDDM fathers. Significant correlations were found between serum triglycerides, HDL-cholesterol and apolipoprotein B, and serum concentrations of pancreatic beta-cell peptides, mostly in the offspring of NIDDM mothers; however, they did not display unequivocal association with gender within this group. The data are consistent with clinical observations of a greater risk of NIDDM transmission from the mother than from the father, and may suggest that male offspring are more exposed to this risk than female offspring. [Diabetologia (1996) 39: 831–837] Received: 2 June 1995 and in final revised form: 19 January 1996     

Assessment of insulin sensitivity and secretion with the labelled intravenous glucose tolerance test: improved modelling analysis

Summary A new modelling analysis was developed to assess insulin sensitivity with a tracer-modified intravenous glucose tolerance test (IVGTT). IVGTTs were performed in 5 normal (NGT) and 7 non-insulin-dependent diabetic (NIDDM) subjects. A 300 mg/kg glucose bolus containing [6,6-²H₂]glucose was given at time 0. After 20 min, insulin was infused for 5 min (NGT, 0.03; NIDDM, 0.05 U/kg). Concentrations of tracer, glucose, insulin and C-peptide were measured for 240 min. A circulatory model for glucose kinetics was used. Glucose clearance was assumed to depend linearly on plasma insulin concentration delayed. Model parameters were: basal glucose clearance (Cl_b), glucose clearance at 600 pmol/l insulin concentration (Cl₆₀₀), basal glucose production (P_b), basal insulin sensitivity index (BSI = Cl_b/basal insulin concentration); incremental insulin sensitivity index (ISI = slope of the relationship between insulin concentration and glucose clearance). Insulin secretion was calculated by deconvolution of C-peptide data. Indices of basal pancreatic sensitivity (PSI_b) and first (PSI₁) and second-phase (PSI₂) sensitivity were calculated by normalizing insulin secretion to the prevailing glucose levels. Diabetic subjects were found to be insulin resistant (BSI: 2.3 ± 0.6 vs 0.76 ± 0.18 ml · min^–1· m^–2· pmol/l^–1, p < 0.02; ISI: 0.40 ± 0.06 vs 0.13 ± 0.05 ml · min^–1· m^–2· pmol/l^–1, p < 0.02; Cl₆₀₀: 333 ± 47 vs 137 ± 26 ml · min^–1· m^–2, p < 0.01; NGT vs NIDDM). P_b was not elevated in NIDDM (588 ± 169 vs 606 ± 123 μmol · min^–1· m^–2, NGT vs NIDDM). Hepatic insulin resistance was however present as basal glucose and insulin were higher. PSI₁ was impaired in NIDDM (67 ± 15 vs 12 ± 7 pmol · min^–1· m^–2· mmol/l^–1, p < 0.02; NGT vs NIDDM). In NGT and in a subset of NIDDM subjects (n = 4), PSI_b was inversely correlated with BSI (r = 0.95, p < 0.0001, log transformation). This suggests the existence of a compensatory mechanism that increases pancreatic sensitivity in the presence of insulin resistance, which is normal in some NIDDM subjects and impaired in others. In conclusion, using a simple test the present analysis provides a rich set of parameters characterizing glucose metabolism and insulin secretion, agrees with the literature, and provides some new information on the relationship between insulin sensitivity and secretion. [Diabetologia (1998) 41: 1029–1039] Received: 17 September 1997 and in final revised form: 28 April 1998     

Left Ventricular Hypertrophy in Non-insulin-dependent Diabetic Patients With and Without Diabetic Nephropathy

The aim of our cross-sectional case–control study was to evaluate putative mechanisms of the increased cardiac morbidity and mortality in NIDDM patients with or without diabetic nephropathy. Fifty-one NIDDM patients with diabetic nephropathy (38 males, age 61 ± 8 years, group 1), 53 NIDDM patients with normoalbuminuria (42 males, 61 ± 7 years, group 2), and 22 non-diabetic control subjects (15 males, 58 ± 8 years, group 3) were investigated. Previous antihypertensive treatment was withdrawn 2 weeks before the study. Left ventricular mass index (LVMI) and systolic function were determined by echocardiography. LVMI was elevated, mean ± SE, in group 1: 157 ± 6 g m⁻², and in group 2: 139 ± 7 g m⁻², as compared with group 3: 95 ± 5 g m⁻² (p < 0.001, for both), and in group 1 as compared with group 2 (p = 0.05). The prevalence of left ventricular hypertrophy (LVH) (LVMI > 131 g m⁻² in men and > 100 g m⁻² in women) was much higher in group 1: 75 % (95 % CI, 60–86), and group 2: 51 % (95 % CI, 37–65), as compared with group 3: 9 % (95 % CI, 1–29) (p < 0.001, for both), and in group 1 as compared with group 2 (p < 0.01). Shortening fraction of the left ventricle, % ± SE, was relatively reduced in group 1: 32.5 ± 1.1 %, and group 2: 33.4 ± 1.1 %, as compared with group 3: 41.2 ± 1.2 % (p < 0.01, for both). In a subgroup of 26 normoalbuminuric normotensive NIDDM patients, LVMI was higher than in 14 normotensive non-diabetic control subjects: 137 ± 10 g m⁻² vs 96 ± 7 g m⁻², respectively (p < 0.005). The prevalence of LVH was 42 % (95 % CI, 23–63) and 14 % (95 % CI, 2–43) (p = 0.07) in these two groups, respectively. In conclusion, normotensive and hypertensive NIDDM patients with and without diabetic nephropathy frequently suffer from LVH and relatively reduced systolic function which may constitute independent risk factors for fatal and non-fatal cardiac events. © 1997 John Wiley & Sons, Ltd.     

Abnormal myocardial kinetics of 123I-heptadecanoic acid in subjects with impaired glucose tolerance

Summary Increased triglyceride accumulation has been observed in the diabetic heart, but it is not known whether the abnormalities in myocardial fatty acid metabolism differ between insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetic patients or whether they are present even prior to overt diabetes. Therefore, we studied myocardial fatty acid kinetics with single-photon emission tomography using ¹²³I-heptadecanoic acid (HDA) in four groups of men: impaired glucose tolerance (IGT) (n = 13, age 53 ± 2 years, mean ± SEM), IDDM (n = 8, age 43 ± 3 years), NIDDM (n = 10, age 51 ± 2 years) and control subjects (n = 8, age 45 ± 4 years). Echocardiography and myocardial perfusion scintigraphy (IGT and NIDDM groups) were performed to study cardiac function and flow. In the IGT subjects, myocardial HDA beta-oxidation index was reduced by 53 % (4.6 ± 0.4 vs 9.7 ± 1.0 μmol · min^–1· 100 g^–1, p < 0.01) and HDA uptake by 34 % (3.7 ± 0.2 vs 5.6 ± 0.3 % of injected dose 100 g, p < 0.01) compared with the control subjects. The fractional HDA amount used for beta-oxidation was lower in the IGT compared with the control subjects (43 ± 4 vs 61 ± 4 %, p < 0.05). NIDDM patients also tended to have a lowered HDA beta-oxidation index, whereas IDDM patients had similar myocardial HDA kinetics compared to the control subjects. Myocardial perfusion imaging during the dipyridamole-handgrip stress was normal both in the IGT and NIDDM groups, indicating that abnormal myocardial perfusion could not explain abnormal fatty acid kinetics. In conclusion, even before clinical diabetes, IGT subjects show abnormalities in myocardial fatty acid uptake and kinetics. These abnormalities may be related to disturbed plasma and cellular lipid metabolism. [Diabetologia (1997) 40: 541–549] Received: 26 August 1996 and in revised form: 21 November 1996     

Renal functional reserve in IDDM patients

Summary The aim of this study was to determine whether renal functional reserve (RFR) is altered in insulin-dependent diabetic (IDDM) patients according to the stage of diabetic nephropathy. RFR was examined in 33 IDDM patients in similar glycaemic and metabolic control and compared to 12 healthy control subjects, during eight 1 h clearance periods prior to, during and after a 3-h stimulation by amino acid infusion (4.5 mg · kg⁻¹· min⁻¹). RFR was calculated as the difference between stimulated and baseline glomerular filtration rates (GFR). In 14 early normotensive diabetic patients with normal urinary albumin excretion, mean baseline GFR (133 ± 3 ml · min⁻¹· 1.73 m⁻²) was higher whereas RFR (10 ± 4 ml · min⁻¹· 1.73 m⁻²) was lower (p < 0.05) than in control subjects (113 ± 4 and 28 ± 2 ml · min⁻¹· 1.73 m⁻², respectively). In 10 normotensive patients who had lived with IDDM for 16 years and who had microalbuminuria, baseline GFR and RFR (109 ± 7 and 24 ± 6 ml · min⁻¹· 1.73 m⁻², respectively) were similar to those in control subjects. In 9 patients who had suffered IDDM for 23 years and had developed macroalbuminuria and hypertension, baseline GFR (78 ± 8 ml · min⁻¹· 1.73 m⁻²) was lower than in control subjects (p < 0.05) and RFR (8 ± 4 ml · min⁻¹· 1.73 m⁻²) was not significant. In addition, renal vascular resistance decreased significantly during infusion (p < 0.05) in microalbuminuric normotensive patients as well as in control subjects (by 9 ± 4 and 11 ± 4 mm Hg · l⁻¹· min⁻¹· 1.73 m⁻², respectively) but not in normoalbuminuric normotensive or macroalbuminuric hypertensive patients. These results indicate that microalbuminuric normotensive patients retain a normal RFR, whereas RFR is reduced or suppressed at two opposite stages of the disease: in normoalbuminuric normotensive patients with a high GFR and in macroalbuminuric hypertensive patients with a decreased GFR. This dissimilar impairment reveals permanent glomerular hyperfiltration in both early IDDM without nephropathy and IDDM with overt diabetic nephropathy, but not in IDDM with incipient nephropathy. [Diabetologia (1998) 41: 86–93] Received: 12 February 1997 and in final revised form: 28 August 1997     

Elevated activity of N -acetylglucosaminyltransferase V in human hepatocellular carcinoma

Cell-surface glycoproteins are regarded as candidates for involvement in the spread of tumor cells. N-linked β1-6 branched oligosaccharides may contribute directly to the malignant or metastatic phenotypes of tumor cells. Increased β1-6 branching has been associated with an increased level of N-acetylglucosaminyltransferase V (GlcNAc transferase V), the glycosyltransferase that initiates the β1-6 branching. In this report, 33 pathologically verified hepatocellular carcinoma (HCC) specimens, six non-cancerous tissues surrounding HCC and five normal liver specimens have been studied. We have quantified N-linked β1-6 branched oligosaccharides indirectly by measuring GlcNac transferase V activity. The average GlcNac transferase V activities in hepatocellular carcinoma (HCC), noncancerous tissues surrounding HCC and normal liver tissues were 324.2 ± 269.8, 84.8 ± 20.7 and 7.0 ± 6.2 pmol product h⁻¹ mg protein⁻¹ (P < 0.05) respectively. In addition, the activity was correlated with the TNM classification of HCC. The average activities of GlcNAc transferase V in stages T1, T2–3 and T4 were 77.6 ± 57.8, 369.0 ± 294.7 and 329.9 ± 205.9 pmol product h⁻¹ mg protein h⁻¹ respectively (P < 0.05), showing that the activity of the enzyme in advanced HCC was higher than that in early HCC. Our preliminary results indicated that GlcNAc transferase V activity increased in human HCC and was correlated with its progression. Received: 5 May 1997 / Accepted: 21 August 1997     

Studies on the mass action effect of glucose in NIDDM and IDDM: evidence for glucose resistance

Summary The ability of hyperglycaemia to enhance glucose uptake was evaluated in 9 non-insulin-dependent (NIDDM), 7 insulin-dependent (IDDM) diabetic subjects, and in 6 young and 9 older normal volunteers. Following overnight insulin-induced euglycaemia, a sequential three-step hyperglycaemic clamp (+ 2.8 + 5.6, and + 11.2 mmol/l above baseline) was performed with somatostatin plus replacing doses of basal insulin and glucagon, 3-³H-glucose infusion and indirect calorimetry. In the control subjects as a whole, glucose disposal increased at each hyperglycaemic step (13.1 ± 0.6, 15.7 ± 0.7, and 26.3 ± 1.1 μmol/kg · min). In NIDDM (10.5 ± 0.2, 12.1 ± 1.0, and 17.5 ± 1.1 μmol/kg · min), and IDDM (11.2 ± 0.8, 12.9 ± 1.0, and 15.6 ± 1.1 μmol/kg · min) glucose disposal was lower during all three steps (p < 0.05–0.005). Hepatic glucose production declined proportionally to plasma glucose concentration to a similar extent in all four groups of patients. In control subjects, hyperglycaemia stimulated glucose oxidation (+ 4.4 ± 0.7 μmol/kg · min) only at + 11.2 mmol/l (p < 0.05), while non-oxidative glucose metabolism increased at each hyperglycaemic step (+ 3.1 ± 0.7; + 3.5 ± 0.9, and + 10.8 ± 1.7 μmol/kg · min; all p < 0.05). In diabetic patients, no increment in glucose oxidation was elicited even at the highest hyperglycaemic plateau (IDDM = + 0.5 ± 1.5; NIDDM = + 0.2 ± 0.6 μmol/kg · min) and non-oxidative glucose metabolism was hampered (IDDM = + 1.8 ± 1.5, + 3.1 ± 1.7, and + 4.3 ± 1.8; NIDDM = + 0.7 ± 0.6, 2.1 ± 0.9, and + 7.0 ± 0.8 μmol/kg · min; p < 0.05–0.005). Blood lactate concentration increased and plasma non-esterified fatty acid (NEFA) fell in control (p < 0.05) but not in diabetic subjects. The increments in blood lactate were correlated with the increase in non-oxidative glucose disposal and with the decrease in plasma NEFA. In conclusion: 1) the ability of hyperglycaemia to promote glucose disposal is impaired in NIDDM and IDDM; 2) stimulation of glucose oxidation and non-oxidative glucose metabolism accounts for glucose disposal; 3) both pathways of glucose metabolism are impaired in diabetic patients; 4) impaired ability of hyperglycaemia to suppress plasma NEFA is present in these patients. These results suggest that glucose resistance, that is the ability of glucose itself to promote glucose utilization, is impaired in both IDDM and NIDDM patients. [Diabetologia (1997) 40: 687–697] Received: 20 August 1996 and in revised form: 5 March 1997     

Urinary Glycosaminoglycan Excretion in NIDDM Subjects: Its Relationship to Albuminura

Nephropathy is a serious microvascular complication of diabetes mellitus which is preceded by a period of microalbuminura. Increased loss of proteoglycan (PG) from glomerular basement (GBM) has been postulated to alter glomerular charge selectivity which contributes to urinary loss of albumin. In this study we measured the excretion of urinary glycosaminoglycans (GAG), the degradation products of PG, in 82 non-insulin-dependent (NIDDM) (Type 2) diabetic and 34 non-diabetic subjects. We found that diabetic subjects had a significantly higher GAG urinary excretion rate compared to non-diabetic subjects (12.54 ± 5.67 vs 8.80 ± 3.99 μg glucuronic acid min⁻¹, p = 0.0001). Categorizing for albuminuric status shows that the diabetic normo-, micro- and macroalbuminuric groups have a higher GAG excretion rate than non-diabetic subjects. Heparan sulphate (HS) GAG urinary excretion was measured in 25 samples from diabetic subjects and 18 non-diabetic subjects. Diabetic subjects excreted more HS GAG than controls both as a rate or as a percentage of total GAG (3.70 ± 1.94 vs 2.38 ± 1.48 μg glucosamine min⁻¹, p = 0.02; 31.6 % ± 12.5 vs 23.1 % ± 10.4, p = 0.02). Categorizing for albuminuric status shows that micro- and macro-albuminuric groups have a significantly higher HS GAG excretion rate than non-diabetic subjects. We conclude that, as in IDDM, excretion of GAG and HS GAG is higher in NIDDM and may precede the development of microalbuminuria.     

Physiological and genetic characterization of the Gly40Ser mutation in the glucagon receptor gene in the Sardinian population

Summary A Gly40Ser amino acid substitution in the glucagon receptor gene has been associated with non-insulin-dependent diabetes mellitus (NIDDM), but the questions raised about its physiological implications have not been resolved. The aim of this study was to determine the frequency of the Gly40Ser mutation in different regions of Sardinia and to investigate the physiological implications of the mutation in glucose and insulin homeostasis. We studied a population of 691 subjects, selected on the basis of their Sardinian origin. Only heterozygous subjects were found, 21 of 574 (3.6 %) in NIDDM patients and 5 of 117 in non-diabetic subjects (4.2 %). In northern Sardinia 3.4 % of the NIDDM patients were carriers of the Gly40Ser substitution, 1.4 % in central Sardinia, while 7.6 % carried the substitution in the Southern part. No significant differences were found between hypertensive and normotensive subjects with respect to the presence of Gly40Ser. Ten subjects with Gly40Ser were carefully matched for diabetic state, BMI, age, sex, and geographical origin with 10 patients with Gly40, and a glucagon infusion test was performed using 1, 3, 9 and 27 ng glucagon kg^–1· min^–1 for 30 min. Blood for determination of glucose, glucagon, and insulin concentrations was drawn at 15-min intervals from the Controlateral arm. Plasma glucagon increased dose-dependently during the infusion with no significant difference between the two groups. Carriers of Gly40Ser had a significantly lower (p < 0.02) increase in plasma glucose concentration in response to glucagon infusion compared to Gly40 homozygous subjects at all times, while the plasma insulin increase was not significantly different at any time. In conclusion, our results indicate that the Gly40Ser variation is not associated with NIDDM in the Sardinian population, and that its frequency varies in different parts of Sardinia. Moreover in vivo Gly40Ser plays a physiological role in the glucose homeostasis under glucagon control both in NIDDM and non-diabetic subjects. This latter result suggests that this amino acid substitution in the glucagon receptor may lead to a decreased blood glucose concentration because of the reduced stimulation of liver glucose output via the glucagon receptor. [Diabetologia (1997) 40: 89–94] Received: 18 July 1996 and in revised form: 15 October 1996     

Insulin resistance is associated with high plasma ouabain-like immunoreactivity concentration in NIDDM

Summary The aim of the present study was to elucidate the pathophysiologic significance of circulating ouabain as a link between insulin resistance (IR) and hypertension (HT) in NIDDM. Euglycaemic (4.5 mmol/l) hyperinsulinaemic (360–580 pmol/l) clamping was performed using an artificial endocrine pancreas. Plasma ouabain-like immunoreactivity (OLI) was determined by radioimmunoassay using a highly specific antibody to ouabain. HT was defined as systolic blood pressure > 140 mm Hg and/or diastolic > 90 mm Hg or being treated with antihypertensive agents. The values (mean ± SEM) of glucose infusion rate (GIR) and plasma OLI were compared among the four groups classified using IR and HT as factors. Group I (IR−/HT−, n = 15):GIR 7.20 ± 0.36 mg · kg⁻¹· min⁻¹, OLI 130.8 ± 20.9 pmol/l, which was not different from that in eight normal control subjects (7.69 ± 0.40 mg · kg⁻¹· min⁻¹ and 142.6 ± 32.3 pmol/l, respectively); Group II (IR−/HT+, n = 13): 5.89 ± 0.36 mg · kg⁻¹· min⁻¹, 172.5 ± 35.0 pmol/l; Group III (IR+/HT−, n = 14) 1.91 ± 0.28 mg · kg⁻¹· min⁻¹, 576.6 ± 161.5 pmol/l (p < 0.01 vs Group I and II); Group IV (IR+/HT+, n = 15) 1.79 ± 0.22 mg · kg⁻¹· min⁻¹, 703.1 ± 170.1 pmol/l (p < 0.01 vs Group I and II), respectively. Six of 57 NIDDM patients studied exhibited very high (> 1500 pmol/l) plasma OLI concentrations, showed marked insulin resistance and were all hypertensive. When analysed as a whole, plasma OLI was negatively correlated with GIR (p < 0.001), but was not correlated with arterial blood pressure. These results demonstrate that plasma concentration of OLI is closely associated with the severity of IR but not with blood pressure elevation. It is, however, possible that in some fraction of NIDDM patients with insulin resistance, the elevation of blood pressure may be causally related to circulating OLI. [Diabetologia (1995) 38: 792–797] Received: 13 September 1994 and in revised form: 9 December 1994