Distinct and shared genetic architectures of Gestational diabetes mellitus and Type 2 Diabetes Mellitus

Gestational diabetes mellitus (GDM) affects more than 16 million pregnancies annually worldwide and is related to an increased lifetime risk of Type 2 diabetes (T2D). The diseases are hypothesized to share a genetic predisposition, but there are few GWAS studies of GDM and none of them is sufficiently powered to assess whether any variants or biological pathways are specific to GDM. We conducted the largest genome-wide association study of GDM to date in 12,332 cases and 131,109 parous female controls in the FinnGen Study and identified 13 GDM-associated loci including 8 novel loci. Genetic features distinct from T2D were identified both at the locus and genomic scale. Our results suggest that the genetics of GDM risk falls into two distinct categories - one part conventional T2D polygenic risk and one part predominantly influencing mechanisms disrupted in pregnancy. Loci with GDM-predominant effects map to genes related to islet cells, central glucose homeostasis, steroidogenesis, and placental expression. These results pave the way for an improved biological understanding of GDM pathophysiology and its role in the development and course of T2D.

A genome-wide association study of anorexia nervosa

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10(-7)) in SOX2OT and rs17030795 (P=5.84 × 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Linkage of nicotine dependence and smoking behavior on 10q, 7q and 11p in twins with homogeneous genetic background

The significant worldwide health burden introduced by tobacco smoking highlights the importance of studying the genetic determinants of smoking behavior and the key factor sustaining compulsive smoking, that is, nicotine dependence (ND). We have here addressed the genetic background of smoking in a special study sample of twins, harmonized for early life events and specifically ascertained for smoking from the nationwide twin cohort of the genetically unique population of Finland. The twins and their families were carefully examined for extensive phenotype profiles and a genome-wide scan was performed to identify loci behind the smoking status, ND and the comorbid phenotype of ND and alcohol use in 505 individuals from 153 families. We replicated previous linkage findings on 10q (max logarithm of the odds (LOD) 3.12) for a smoker phenotype, and on 7q and 11p (max LOD 2.50, and 2.25, respectively) for the ND phenotype. The loci linked for ND also showed evidence for linkage for the comorbid phenotype. Our study provides confirmatory evidence for the involvement of these genome regions in the genetic etiology of smoking behavior and ND and for the first time associates drinking and smoking to a shared locus on 10q.

Genomewide search for type 2 diabetes mellitus susceptibility loci in Finnish families: the Botnia study

Type 2 diabetes mellitus is a heterogeneous inherited disorder characterized by chronic hyperglycemia resulting from pancreatic beta-cell dysfunction and insulin resistance. Although the pathogenic mechanisms are not fully understood, manifestation of the disease most likely requires interaction between both environmental and genetic factors. In the search for such susceptibility genes, we have performed a genomewide scan in 58 multiplex families (comprising 440 individuals, 229 of whom were affected) from the Botnia region in Finland. Initially, linkage between chromosome 12q24 and impaired insulin secretion had been reported, by Mahtani et al., in a subsample of 26 families. In the present study, we extend the initial genomewide scan to include 32 additional families, update the affectation status, and fine map regions of interest, and we try to replicate the initial stratification analysis. In our analysis of all 58 families, we identified suggestive linkage to one region, chromosome 9p13-q21 (nonparametric linkage [NPL] score 3.9; P<.0002). Regions with nominal P values <.05 include chromosomes 2p11 (NPL score 2.0 [P<.03]), 3p24-p22 (NPL score 2.2 [P<.02]), 4q32-q33 (NPL score 2.5 [P<.01]), 12q24 (NPL score 2.1 [P<.03]), 16p12-11 (NPL score 1.7 [P<.05]), and 17p12-p11 (NPL score 1.9 [P<.03]). When chromosome 12q24 was analyzed in only the 32 additional families, a nominal P value <.04 was observed. Together with data from other published genomewide scans, these findings lend support to the hypothesis that regions on chromosome 9p13-q21 and 12q24 may harbor susceptibility genes for type 2 diabetes.

A dominant gene for developmental dyslexia on chromosome 3

Developmental dyslexia is a neurofunctional disorder characterised by an unexpected difficulty in learning to read and write despite adequate intelligence, motivation, and education. Previous studies have suggested mostly quantitative susceptibility loci for dyslexia on chromosomes 1, 2, 6, and 15, but no genes have been identified yet. We studied a large pedigree, ascertained from 140 families considered, segregating pronounced dyslexia in an autosomal dominant fashion. Affected status and the subtype of dyslexia were determined by neuropsychological tests. A genome scan with 320 markers showed a novel dominant locus linked to dyslexia in the pericentromeric region of chromosome 3 with a multipoint lod score of 3.84. Nineteen out of 21 affected pedigree members shared this region identical by descent (corrected p<0.001). Previously implicated genomic regions showed no evidence for linkage. Sequencing of two positional candidate genes, 5HT1F and DRD3, did not support their role in dyslexia. The new locus on chromosome 3 is associated with deficits in all three essential components involved in the reading process, namely phonological awareness, rapid naming, and verbal short term memory.

High frequency of mutations in MODY and mitochondrial genes in Scandinavian patients with familial early-onset diabetes

AIMS/HYPOTHESIS

To investigate the contribution of mutations in maturity-onset diabetes of the young (MODY) and mitochondrial genes to early-onset diabetes with a strong family history of diabetes in a cohort with a high prevalence of Type I (insulin-dependent) diabetes mellitus.

METHODS

Screening for sequence variants in the hepatocyte nuclear factor (HNF)-4alpha (MODY1), glucokinase (MODY2), HNF-1alpha (MODY3) genes and mitochondrial DNA was carried out in 115 Finnish and Swedish patients with early-onset ( </= 40 years) diabetes using the single strand conformation polymorphism (SSCP) technique and direct sequencing. Allele frequencies were compared with 118 patients with onset of diabetes Type II (non-insulin-dependent) diabetes mellitus after the age of 40 and 92 non-diabetic control subjects without a family history of diabetes.

RESULTS

In total 52 sequence variants were found in the HNF-1alpha, HNF-4alpha and glucokinase genes, 12 of which were considered as MODY mutations. Three families had the A3243G mutation in the mitochondrial tRNA(Leu) gene, which resulted in an overall prevalence of these mutations of 13 %.

CONCLUSION/INTERPRETATION

Among 115 Scandinavian families, mutations in the HNF-1alpha gene represented the most common cause of familial early-onset ( </= 40 years) diabetes: MODY3 (5.2 %) more than MODY2 (3.5 %) more than MIDD (2.6 %) more than MODY1 (1.7 %).

Characterization of the MODY3 phenotype. Early-onset diabetes caused by an insulin secretion defect

Maturity-onset diabetes of the young (MODY) type 3 is a dominantly inherited form of diabetes, which is often misdiagnosed as non-insulin-dependent diabetes mellitus (NIDDM) or insulin-dependent diabetes mellitus (IDDM). Phenotypic analysis of members from four large Finnish MODY3 kindreds (linked to chromosome 12q with a maximum lod score of 15) revealed a severe impairment in insulin secretion, which was present also in those normoglycemic family members who had inherited the MODY3 gene. In contrast to patients with NIDDM, MODY3 patients did not show any features of the insulin resistance syndrome. They could be discriminated from patients with IDDM by lack of glutamic acid decarboxylase antibodies (GAD-Ab). Taken together with our recent findings of linkage between this region on chromosome 12 and an insulin-deficient form of NIDDM (NIDDM2), the data suggest that mutations at the MODY3/NIDDM2 gene(s) result in a reduced insulin secretory response, that subsequently progresses to diabetes and underlines the importance of subphenotypic classification in studies of diabetes.

Mapping of a gene for type 2 diabetes associated with an insulin secretion defect by a genome scan in Finnish families

Non-insulin dependent diabetes mellitus (NIDDM) affects more than 100 million people worldwide and is associated with severe metabolic defects, including peripheral insulin resistance, elevated hepatic glucose production, and inappropriate insulin secretion. Family studies point to a major genetic component, but specific susceptibility genes have not yet been identified-except for rare early-onset forms with monogenic or mitochondrial inheritance. We have screened over 4,000 individuals from a population isolate in western Finland, identified 26 families (comprising 217 individuals) enriched for NIDDM and performed a genome-wide scan using non-parametric linkage analysis. We found no significant evidence for linkage when the families were analysed together, but strong evidence for linkage when families were classified according to mean insulin levels in affecteds (in oral glucose tolerance tests). Specifically, families with the lowest insulin levels showed linkage (P = 2 x 10(-6)) to chromosome 12 near D12S1349. Interestingly, this region contains the gene causing the rare, dominant, early-onset form of diabetes MODY3. Unlike MODY3 families, the Finnish families with low insulin have an age-of-onset typical for NIDDM (mean = 58 years). We infer the existence of a gene NIDDM2 causing NIDDM associated with low insulin secretion, and suggest that NIDDM2 and MODY3 may represent different alleles of the same gene.

The effect of (steroid) immunosuppression on skeletal muscle glycogen metabolism in patients after kidney transplantation

To examine the mechanisms by which immunosuppression by steroids impairs glycogen synthesis in human skeletal muscle, we measured glycogen synthase protein content and activity in muscle samples from 14 patients receiving corticosteroid therapy after kidney transplantation and in 20 healthy control subjects. A percutaneous muscle sample was taken before and at the end of a euglycemic hyperinsulinemic insulin clamp. Insulin-stimulated glucose disposal was reduced by 33% in kidney transplant patients compared with healthy controls (33.8 +/- 4.2 vs. 50.5 +/- 2.7 mumol (kg LBM)-1 min-1; P<0.01), primarily due to a decrease in nonoxidative glucose metabolism (14.2 +/- 3.3 vs. 32.3 +/- 2.7 mumol (kg LBM)-1 min-1; P<0.001). Glycogen synthase activity measured at both 0.1 mmol/L (17.6 +/- 2.6 vs. 24.0 +/- 2.2 nmol min-1 mg protein-1; P<0.05), and at 10 mmol/L glucose 6-phosphate (24.1 +/- 3.5 vs. 33.7 +- 2.4 nmol min-1 mg protein-1; P<0.05) and glycogen synthase protein concentrations (8.8 +/- 1.8 vs. 18.9 +/- 1.9 relative units per ng DNA; P<0.01) were lower in kidney transplant patients compared with controls. Glycogen synthase protein correlated with nonoxidative glucose metabolism (r=0.42; P=0.04). Alpha-actinin (used as a control of general protein degradation) was lower in kidney transplant patients compared with controls (4.4 +/- 0.8 vs. 9.6 +/- 1.1 cpm/ng DNA; P<0.01). In conclusion, corticosteroids cause insulin resistance, which correlates with impaired activation of glycogen synthase and decreased enzyme protein content. The decrease in glycogen synthase protein may reflect increased degradation rather than a defect in translation.

Association of a polymorphism in the beta 3-adrenergic-receptor gene with features of the insulin resistance syndrome in Finns

BACKGROUND

Because visceral obesity predicts insulin resistance, we studied whether alterations in the gene encoding for the beta 3-adrenergic receptor in visceral fat are associated with insulin resistance.

METHODS

We studied the frequency of a cytosine-to-thymidine mutation that results in the replacement of tryptophan by arginine at position 64 (Trp64Arg) of the beta 3-adrenergic receptor by restriction-enzyme digestion with BstOl in 335 subjects from western Finland, 207 of whom were nondiabetic and 128 of whom had non-insulin-dependent diabetes mellitus (NIDDM). We also determined the frequency of the mutation in 156 subjects from southern Finland. Sensitivity to insulin was measured by the hyperinsulinemic-euglycemic clamp technique in 66 randomly selected nondiabetic subjects.

RESULTS

In the subjects from western Finland, the frequency of the mutated allele was similar in the nondiabetic subjects and the subjects with NIDDM (12 vs. 11 percent). The mean age of the subjects at the onset of diabetes was lower among those with the mutation than those without it (56 vs. 61 years, P = 0.04). Among the nondiabetic subjects, those with the mutation had a higher ratio of waist to hip circumference (P = 0.02), a greater increase in the serum insulin response after the oral administration of glucose (P = 0.05), a higher diastolic blood pressure (82 vs. 78 mm Hg, P = 0.01), and a lower rate of glucose disposal during the clamp study (5.3 vs. 6.5 mg [29 vs. 36 mumol] per kilogram of body weight per minute; P = 0.04) than the subjects without the mutated allele. In an analysis of sibling pairs, the siblings with the mutation generally had higher waist:hip ratios (P = 0.05) and higher responses of blood glucose and serum insulin after the oral administration of glucose than their siblings without the mutation (P = 0.02 and P = 0.005, respectively).

CONCLUSIONS

The Trp64Arg allele of the beta 3-adrenergic receptor is associated with abdominal obesity and resistance to insulin and may contribute to the early onset of NIDDM:

Insulin resistance, hypertension and microalbuminuria in patients with type 2 (non-insulin-dependent) diabetes mellitus

We examined the impact of hypertension and microalbuminuria on insulin sensitivity in patients with Type 2 (non-insulin-dependent) diabetes mellitus using the euglycaemic insulin clamp technique in 52 Type 2 diabetic patients and in 19 healthy control subjects. Twenty-five diabetic patients had hypertension and 19 had microalbuminuria. Hypertension per se was associated with a 27% reduction in the rate of total glucose metabolism and a 40% reduction in the rate of non-oxidative glucose metabolism compared with normotensive Type 2 diabetic patients (both p < 0.001). Glucose metabolism was also impaired in normotensive microalbuminuric patients compared with normotensive normoalbuminuric patients (29.4 +/- 2.2 vs 40.5 +/- 2.8 mumol.kg lean body mass-1.min-1; p = 0.012), primarily due to a reduction in non-oxidative glucose metabolism (12.7 +/- 2.9 vs 21.1 +/- 2.6 mumol.kg lean body mass-1.min-1; p = 0.06). In a factorial ANOVA design, however, only hypertension (p = 0.008) and the combination of hypertension and microalbuminuria (p = 0.030) were significantly associated with the rate of glucose metabolism. The highest triglyceride and lowest HDL cholesterol concentrations were observed in Type 2 diabetic patients with both hypertension and microalbuminuria. Of note, glucose metabolism was indistinguishable from that in control subjects in Type 2 diabetic patients without hypertension and microalbuminuria (40.5 +/- 2.8 vs 44.4 +/- 2.8 mumol.kg lean body mass-1.min-1). We conclude that insulin resistance in Type 2 diabetes is predominantly associated with either hypertension or microalbuminuria or with both.

Does glibenclamide influence the clearance of insulin and glucose uptake in patients with type 2 diabetes mellitus?

Sulphonylureas have been proposed to decrease the clearance of insulin based on the finding that they increase peripheral insulin concentrations more than C-peptide concentrations. However, direct evidence for such an effect has so far been lacking. The aim of this study was to investigate whether glibenclamide affects clearance of insulin in Type 2 diabetic patients. Nine patients with Type-2 diabetes participated in the study. Insulin clearance and glucose metabolism was assessed with a 240 min euglycaemic insulin clamp in combination with infusion of somatostatin (400 micrograms h-1) to completely suppress endogenous insulin secretion. Either saline or glibenclamide was infused throughout the clamp in random order. During both the glibenclamide and the saline protocol the C-peptide level declined to < 0.07 nmol l-1 within 150 min, indicating that insulin secretion was completely suppressed. However, peripheral clamp insulin concentrations remained similar during both saline and glibenclamide protocols (3374 +/- 258 vs. 3350 +/- 265 pmol l-1 x 240 min, p = NS). There was no significant difference in the metabolic clearance rate of insulin during the glibenclamide compared to the saline experiment neither during the first 120 min (796 +/- 36 vs. 757 +/- 34 ml m-2min-1) nor during the last 2 h of the clamp (780 +/- 43 vs. 724 +/- 35 ml m-2min-1). Total glucose metabolism during the first two (14 +/- 2 vs. 15 +/- 2 mumol kg-1 min-1) and the last 2 h of the clamp was similar both during saline and glibenclamide infusions (27 +/- 4 vs. 28 +/- 4 mumol kg-1min-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of muscle and liver to glucose-fatty acid cycle in humans

To examine the influence of elevated free fatty acid (FFA) levels on hepatic glucose production (HGP) and oxidative and nonoxidative pathways of glucose metabolism, 12 healthy subjects participated in two euglycemic insulin-clamp studies performed with and without infusion of Intralipid plus heparin. To elucidate the role of skeletal muscle in this putative interaction, we performed muscle biopsies for the measurement of activities of glycogen synthase (GS), pyruvate dehydrogenase (PDH), and carnitine palmitoyltransferase (CPT). Infusion of Intralipid plus heparin caused an increase in plasma FFA concentrations and rate of lipid oxidation (measured by indirect calorimetry) that was not inhibited by insulin. Suppression of HGP by insulin was impaired by elevated plasma FFA levels. Furthermore, the increase in plasma FFA was associated with a 20% reduction in total glucose metabolism (P < 0.01), which was completely accounted for by a reduction in the rate of glucose oxidation. Although the fractional activity of GS was increased by insulin, elevation of plasma FFA had no influence on this key enzyme of glycogen synthesis. In addition, the activities of PDH and CPT were uninfluenced by the elevation of FFA, suggesting that oxidative processes in skeletal muscle were not a major target for the operative glucose-fatty acid cycle under the current conditions. Taken together, the data indicate that the interaction between FFA and glucose metabolism also involves impaired suppression of HGP by insulin.

Association between polymorphism of the glycogen synthase gene and non-insulin-dependent diabetes mellitus

BACKGROUND

The storage of glucose as glycogen in skeletal muscle is frequently impaired in patients with non-insulin-dependent diabetes mellitus (NIDDM) and their nondiabetic relatives. Despite an intensive search for candidate genes associated with NIDDM, no data have been available on the gene coding for the key enzyme of this pathway, glycogen synthase.

METHODS AND RESULTS

Using a human complementary DNA probe, the restriction enzyme Xbal, and Southern blot analysis, we identified two polymorphic alleles, A1 and A2, in the glycogen synthase gene. The gene was localized to chromosome 19. The A1A2 or A2A2 genotype was found in 30 percent of 107 patients with NIDDM but in only 8 percent of 164 nondiabetic subjects without a family history of NIDDM (P < 0.001). The diabetic patients with the A2 allele had a stronger family history of NIDDM (P = 0.019), a higher prevalence of hypertension (P = 0.008), and a more severe defect in insulin-stimulated glucose storage (P = 0.001) than the diabetic patients with the A1 allele. The concentration of the glycogen synthase protein in biopsy specimens of skeletal muscle from the patients with the A2 allele was normal, however, suggesting that expression of the gene was unaltered. The Xbal polymorphism was due to a change of a single base in an intron.

CONCLUSIONS

The Xbal polymorphism of the glycogen synthase gene identifies a subgroup of patients with NIDDM characterized by a strong family history of NIDDM, a high prevalence of hypertension, and marked insulin resistance.

Insulin resistance in type 2 (non-insulin-dependent) diabetic patients with hypertriglyceridaemia

Hypertriglyceridaemia, which is frequently seen in Type 2 (non-insulin-dependent) diabetes mellitus, is associated with insulin resistance. The connection between hypertriglyceridaemia and insulin resistance is not clear, but could be due to substrate competition between glucose and lipids. To address this question we measured glucose and lipid metabolism in 39 Type 2 diabetic patients with hypertriglyceridaemia, i.e. mean fasting serum triglyceride level equal to or above 2 mmol/l (age 59 +/- 1 years, BMI 27.4 +/- 0.5 kg/m2, HbA1c 8.0 +/- 0.2%, serum triglycerides 3.2 +/- 0.2 mmol/l) and 41 Type 2 diabetic patients with normotriglyceridaemia, i.e. mean fasting serum triglyceride level below 2 mmol/l (age 58 +/- 1 years, BMI 27.0 +/- 0.7 kg/m2, HbA1c 7.8 +/- 0.2%, serum triglycerides 1.4 +/- 0.1 mmol/l). Insulin sensitivity was assessed using a 340 pmol.(m2)-1 x min-1 euglycaemic insulin clamp. Substrate oxidation rates were measured with indirect calorimetry and hepatic glucose production was estimated using a primed (25 microCi)-constant (0.25 microCi/min) infusion of [3-3H]-glucose. Suppression of lipid oxidation by insulin was impaired in patients with hypertriglyceridaemia vs patients with normal triglyceride levels (3.5 +/- 0.2 vs 3.0 +/- 0.2 mumol.kg-1 x min-1; p < 0.05). Stimulation of glucose disposal by insulin was reduced in hypertriglyceridaemic vs normotriglyceridaemic patients (27.0 +/- 1.3 vs 31.9 +/- 1.6 mumol.kg-1 x min-1; p < 0.05) primarily due to impaired glucose storage (9.8 +/- 1.0 vs 14.6 +/- 1.4 mumol.kg-1 x min-1; p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Morning or bedtime NPH insulin combined with sulfonylurea in treatment of NIDDM

OBJECTIVE

To compare the effect of morning and bedtime NPH insulin combined with daytime sulfonylurea on glycemic control in non-insulin-dependent diabetes mellitus (NIDDM) patients no longer responding to treatment with sulfonylureas alone.

RESEARCH DESIGN AND METHODS

Twenty-four NIDDM patients who fulfilled these criteria were randomized to treatment with Protaphan human insulin in the morning or at bedtime (22 +/- 1 IU) plus 3.5 mg glibenclamide twice a day.

RESULTS

Morning and bedtime NPH insulin resulted in equal reduction of HbA1 (from 13.5 +/- 0.3 to 9.4 +/- 0.1 and 9.6 +/- 0.2%, respectively) and mean self-monitored blood glucose (9.2 +/- 0.5 vs. 10.1 +/- 0.4 mM). Bedtime insulin resulted in lower morning blood glucose (7.8 +/- 0.5 vs. 9.1 +/- 0.4 mM; P less than 0.01), whereas morning insulin resulted in lower evening blood glucose (10.1 +/- 0.6 vs 12.1 +/- 0.6 mM, P less than 0.01).

CONCLUSIONS

Morning and bedtime NPH insulin combined with glibenclamide are equipotent in the treatment of NIDDM patients with secondary failure to sulfonylurea. However, this treatment regimen normalizes blood glucose only in a small group of patients. Therefore, more intensified insulin therapy seems to be required to achieve this goal.

Pancreatic surgery, not pancreatitis, is the primary cause of diabetes after acute fulminant pancreatitis

Acute fulminant pancreatitis is associated with significant morbidity and mortality. To examine the outcome of conservative and surgical treatment of this disorder, 36 patients who survived an initial episode were restudied after a mean of six years. Fifty three per cent had developed diabetes mellitus, half of whom required insulin therapy. Pancreatic resection was associated with a 100% frequency of diabetes, while only 26% of those treated with peritoneal lavage developed this (p less than 0.001). Insulin secretion and sensitivity were assessed using the hyperglycaemic glucose clamp technique. First phase insulin secretion was impaired in surgically treated patients (mean (SEM) 14 (5) microU/ml x 10 minutes) compared with conservatively treated patients and control subjects (144 (66) and 87 (12) microU/ml x 10 minutes, respectively; p less than 0.05). Second phase and 'maximal' insulin secretion were also impaired among the surgically treated patients compared with the conservatively treated patients and the controls. Insulin sensitivity was reduced among the surgically treated patients (2.88 (58) mg/kg.minute) when compared with conservatively treated patients and healthy control subjects (5.87 (1.02) and 6.45 (0.66) mg/kg.minute; p less than 0.05). Pancreatic resection is associated with a very high frequency of diabetes compared with peritoneal lavage, and these results favour conservative treatment of active fulminant pancreatitis whenever possible.

Insulin resistance in type 2 (non-insulin-dependent) diabetic patients and their relatives is not associated with a defect in the expression of the insulin-responsive glucose transporter (GLUT-4) gene in human skeletal muscle

To study whether insulin resistance in Type 2 (non-insulin-dependent) diabetes mellitus is due to a defect in the expression of the insulin-responsive glucose transporter gene (GLUT-4) in human skeletal muscle, we measured the level of GLUT-4 mRNA and (in some of the subjects) its protein in muscle biopsies taken from 14 insulin-resistant patients with Type 2 diabetes, 10 first-degree relatives of the diabetic patients and 12 insulin-sensitive control subjects. Insulin sensitivity was measured with a + 45 mU.m2(-1).min-1 euglycaemic insulin clamp in combination with indirect calorimetry and infusion of [3-3H]glucose. GLUT-4 mRNA was measured using a human GLUT-4 cDNA probe and GLUT-4 protein with a polyclonal antibody specific for the 15 amino acid carboxy-terminal peptide. Both Type 2 diabetic patients and their relatives showed impaired stimulation of total-body glucose disposal by insulin compared with control subjects (29.5 +/- 2.1 and 34.0 +/- 4.8 vs 57.9 +/- 3.1 mumol.kg lean body mass-1.min-1; p less than 0.01). This impairment in glucose disposal was primarily accounted for by a reduction in insulin-stimulated storage of glucose as glycogen (13.0 +/- 2.4 and 15.6 +/- 3.9 vs 36.9 +/- 2.2 mumol.kg lean body mass-1.min-1; p less than 0.01). The levels of GLUT-4 mRNA expressed both per microgram of total RNA and per microgram DNA, were higher in the diabetic patients compared with the control subjects (116 +/- 25 vs 53 +/- 10 pg/microgram RNA and 177 +/- 35 vs 112 +/- 29 pg/microgram DNA; p less than 0.05, p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Fuel metabolism in anorexia nervosa and simple obesity

To examine insulin sensitivity and the relative contribution of different fuels to energy metabolism in anorexia nervosa and obesity, we measured oxidation (indirect calorimetry) of glucose, lipids, and proteins in the basal state and during an insulin clamp (+45 mU/m2.min) in 11 women with anorexia nervosa (age, 25 +/- 3 years; body mass index [BMI], 13.6 +/- 0.4 kg/m2; fat mass, 15.7% +/- 1.6%), eight obese women (age, 31 +/- 3; BMI 36.0 +/- 1.5; fat mass, 47.1% +/- 1.9%), and eight controls (age, 26 +/- 3; BMI, 21.8 +/- 0.9; fat mass, 25.7% +/- 3.6%). Expressed per lean body mass, (LBM), glucose disposal was equally reduced in anorectics (7.53 +/- 0.62 mg/kg LBM.min) and obese (6.80 +/- 1.07 mg/kg LBM.min) compared with controls (10.64 +/- 0.69 mg/kg LBM.min; P less than .01). The reduction in glucose disposal in anorectics was primarily due to a significant (P less than .01) reduction in glucose storage, while glucose oxidation was normal. In obese women, both storage and oxidation of glucose were reduced compared with controls (P less than .01). Basal energy expenditure was similar in anorectic, obese, and control subjects (20.6 +/- 1.00, 23.7 +/- 0.56, 23.2 +/- 1.36 cal/kg LBM.min, respectively). However, the contribution of glucose, lipids, and proteins to basal energy expenditure differed between anorectic (62%, 16%, 22%), obese (26%, 58%, 16%), and control (30%, 54%, 16%) subjects (P less than .05 v all). In conclusion, in anorexia nervosa, insulin stimulates glucose oxidation more than storage. In obesity, both components of insulin-stimulated glucose metabolism are impaired.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment strategies for secondary sulfonylurea failure. Should we start insulin or add metformin? Is there a place for intermittent insulin therapy?

Which therapy should be used in non-insulin dependent diabetes mellitus (NIDDM) with secondary sulfonylurea failure? Should we start insulin therapy, try a period of intensified insulin therapy and then switch back to sulfonylurea or should we add metformin therapy? To address this question, we have compared these three treatment strategies in 36 NIDDM patients who failed on treatment with sulfonylureas during a 6 month period. Insulin (short and intermediate-acting insulin before breakfast and dinner) and the combination of 21 mg of glibenclamide and 1.5 g of metformin resulted in an equivalent 30% improvement in glycemic control without significant effects on lipids. Intensified insulin therapy (6 weeks of intermediate and short-acting insulin 3 times daily), on the other hand, initially lowered blood glucose to the same degree as during the other two treatment regimes, but after switching back to sulfonylurea therapy (21 mg of glibenclamide/day) blood glucose concentrations returned to pretreatment values. Insulin therapy resulted in a 5 kg increase in body weight, 63% of which was accounted for by an increase in fat mass. Although body weight was unchanged during glibenclamide/sulfonylurea therapy, lean body mass and energy expenditure decreased significantly (p less than 0.05). Body weight and energy metabolism remained unchanged during intermittent insulin therapy.

CONCLUSIONS

Despite similar blood glucose lowering properties, insulin and the combination of sulfonylurea and metformin have different effects on energy metabolism and body composition. Since these effects were not observed during treatment with sulfonylurea alone, they must be ascribed to metformin.

Non-esterified fatty acids do not contribute to insulin resistance in persons at increased risk of developing type 2 (non-insulin-dependent) diabetes mellitus

The mechanisms underlying insulin resistance in Type 2 (non-insulin-dependent) diabetes mellitus are not fully understood. An enhanced lipid/non-esterified fatty acid oxidation could provide an explanation. To test this hypothesis we examined the relationship between glucose and lipid metabolism in 44 first-degree relatives (28 glucose-tolerant and 16 glucose-intolerant) of Type 2 diabetic patients and in 18 healthy control subjects. Total body glucose disposal was impaired among both glucose-tolerant and glucose-intolerant relatives compared with control subjects (36.3 +/- 3.8 and 30.4 +/- 2.7 vs 47.7 +/- 3.4 mumol.kgLBM-1. min-1; p less than 0.05). The impairment in glucose disposal among the relatives was primarily accounted for by impaired non-oxidative glucose metabolism (14.8 +/- 3.0 and 12.5 +/- 1.8 vs 25.3 +/- 3.1 mumol.kgLBM-1.min-1; p less than 0.05). Plasma non-esterified fatty acid concentrations were similar in both glucose-tolerant and glucose-intolerant relatives and control subjects (646 +/- 36, 649 +/- 43 and 615 +/- 41 mumol/l) and showed the same degree of suppression by insulin (99 +/- 8, 86 +/- 7 and 84 +/- 9 mumol/l). Basal lipid oxidation was similar in all groups (1.29 +/- 0.09, 1.52 +/- 0.13 and 1.49 +/- 0.21 mumol.kgLBM-1. min-1). Furthermore, insulin suppressed lipid oxidation to the same degree in glucose-tolerant, glucose-intolerant relatives and control subjects (0.65 +/- 0.13, 0.88 +/- 0.15 and 0.59 +/- 0.09 mumol.kgLBM-1.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sulphonylurea on glucose-stimulated insulin secretion in healthy and non-insulin dependent diabetic subjects: a dose-response study

The effect of a rapid-acting sulphonylurea, glipizide, on the dose-response relationship between the beta-cell response (insulin and C-peptide secretion) and the ambient plasma glucose concentration was examined in 12 healthy and 6 non-insulin-dependent diabetic subjects. The subjects participated in two sets of experiments which were performed in random order: (A) four hyperglycaemic clamp studies, during which the plasma glucose concentration was raised for 120 min by 1 (only in healthy subjects), 3, 7, and 17 mmol/l; and (B) the same four hyperglycaemic clamp studies preceded by ingestion of 5 mg glipizide. All subjects participated in a further study, in which glipizide was ingested and the plasma glucose concentration was maintained at the basal level. In control subjects in the absence of glipizide, the first-phase plasma insulin response (0-10 min) increased progressively with increasing plasma glucose concentration up to 10 mmol/l, above which it tended to plateau. Glipizide augmented the first-phase insulin response without changing the slope of the regression line relating plasma insulin to glucose concentrations. The second-phase plasma insulin response (20-120 min) increased linearly with increasing hyperglycaemia (r = 0.997). Glipizide alone increased the plasma insulin response by 180 pmol/l. A similar increase in plasma insulin response following glipizide was observed at each hyperglycaemic step, indicating that glipizide did not affect the sensitivity of the beta-cell to glucose. First-phase insulin secretion was reduced in the type 2 (non-insulin-dependent) diabetic patients, and was not influenced by glipizide.(ABSTRACT TRUNCATED AT 250 WORDS)

Early metabolic defects in persons at increased risk for non-insulin-dependent diabetes mellitus

To identify early metabolic abnormalities in non-insulin-dependent diabetes mellitus (NIDDM), we measured sensitivity to insulin and insulin secretion in 26 first-degree relatives of patients with NIDDM and compared these subjects both with 14 healthy control subjects with no family history of NIDDM and with 19 patients with NIDDM. The euglycemic insulin-clamp technique, indirect calorimetry, and infusion of [3-3H]glucose were used to assess insulin sensitivity. Total-body glucose metabolism was impaired in the first-degree relatives as compared with the controls (P less than 0.01). The defect in glucose metabolism was almost completely accounted for by a defect in nonoxidative glucose metabolism (primarily the storage of glucose as glycogen). The relatives with normal rates of metabolism (mean +/- SEM, 1.81 +/- 0.27 mg per kilogram of body weight per minute) and impaired rates (1.40 +/- 0.22 mg per kilogram per minute) in oral glucose-tolerance tests had the same degree of impairment in glucose storage as compared with healthy control subjects (3.76 +/- 0.55 mg per kilogram per minute; P less than 0.01 for both comparisons). During hyperglycemic clamping, first-phase insulin secretion was lacking in patients with NIDDM (P less than 0.01) and severely impaired in their relatives with impaired glucose tolerance (P less than 0.05) as compared with control subjects; insulin secretion was normal in the relatives with normal glucose tolerance. We conclude that impaired glucose metabolism is common in the first-degree relatives of patients with NIDDM, despite their normal results on oral glucose-tolerance tests. Both insulin resistance and impaired insulin secretion are necessary for the development of impaired glucose tolerance in these subjects.

Characteristics of non-insulin-dependent diabetic patients with secondary failure to oral antidiabetic therapy

PURPOSE

Secondary failure to treatment with oral antidiabetic agents frequently occurs in patients with non-insulin-dependent diabetes mellitus. In the search for causes of such failures, we examined patient- and disease-related factors in nonresponders and in responders to treatment with oral antidiabetic agents.

PATIENTS AND METHODS

The study population consisted of three groups: (1) 34 nonresponders to treatment with sulfonylureas; (2) 25 patients who still responded to treatment with sulfonylureas; and (3) 10 age-matched healthy control subjects. In addition to patient-related factors such as adherence to diet and knowledge of diabetes, we examined insulin response to a test meal and hepatic and peripheral insulin sensitivity during a euglycemic insulin clamp in combination with indirect calorimetry and infusion of [3H-3-]glucose.

RESULTS

Patient-related factors such as daily nutrient intake, activity score, knowledge of diabetes, and "stress level" were similar in both groups. However, nonresponders had a higher rate of basal hepatic glucose production (4.60 +/- 0.14 versus 3.63 +/- 0.26 mg/minute/kg of lean body weight; p less than 0.001), which was less suppressed by euglycemic hyperinsulinemia (about 100 microU/mL) than was that of the responders (p less than 0.001). In addition, total insulin-stimulated glucose metabolism was reduced (5.07 +/- 0.22 versus 7.09 +/- 0.56 mg/kg.LBM.minute; p less than 0.001), and this was mainly accounted for by a reduction in non-oxidative glucose metabolism (glycogen synthesis and anaerobic glycolysis) (1.78 +/- 0.22 versus 3.54 +/- 0.49 mg/kg.LBM.minute; p less than 0.001). The severity of hepatic and peripheral insulin resistance correlated with the plasma glucose concentration but was unrelated to insulin secretion. In a multiple linear regression analysis, glucose overproduction in the liver (26.1%), impaired peripheral glucose metabolism (17.3%), and insulin deficiency (12.6%) could explain only 56% of the causes of secondary drug failure.

CONCLUSION

Secondary failure to treatment with oral hypoglycemic agents is determined by the disease itself rather than by patient-related factors. Treatment of secondary drug failure should therefore aim at ameliorating both hepatic and peripheral insulin resistance.

Different effects of insulin and oral antidiabetic agents on glucose and energy metabolism in type 2 (non-insulin-dependent) diabetes mellitus

Which therapy should be used in Type 2 (non-insulin-dependent) diabetic patients with "secondary sulfonylurea failure", insulin or a combination of sulfonylurea and metformin? To address this question, we have compared the effect of 6 months of insulin therapy twice daily with that of a combination of glibenclamide and metformin in 24 Type 2 diabetic subjects, who no longer responded to treatment with sulfonylureas. Both treatments resulted in an equivalent 30% improvement in mean daily blood glucose (p less than 0.001), without significant effect on serum lipids. Insulin improved glycaemic control primarily by reducing basal hepatic glucose production (p less than 0.05), but had no significant effect on peripheral glucose metabolism. The combination of glibenclamide and metformin enhanced significantly total body glucose metabolism (p less than 0.05), predominantly by stimulating the non-oxidative pathway. Neither insulin nor the combination therapy altered B-cell response to a test meal. Insulin therapy resulted in a 6% increase in body weight, 63% of which was accounted for by increased fat mass. Although body weight was unchanged during sulfonylurea/metformin therapy, lean body mass and energy expenditure decreased significantly (p less than 0.05). We conclude that insulin and glibenclamide/metformin have different long-term effects on glucose and energy metabolism in Type 2 diabetes.