The estrogen receptor α-selective agonist propyl pyrazole triol improves glucose tolerance in ob/ob mice: potential molecular mechanisms

The authors and journal apologise for an error in the above paper, which appeared in volume 199 part 2, pages 275­286. The error relates to Fig. 10, given on page 283.

Sitagliptin improves beta-cell function in patients with acute coronary syndromes and newly diagnosed glucose abnormalities--the BEGAMI study.

BACKGROUND: Newly detected impaired glucose tolerance (IGT) or type 2 diabetes mellitus (T2DM) are common in patients with acute coronary syndrome (ACS; i.e. unstable angina/myocardial infarction) and related to disturbed beta-cell function. The aim of this study is to test the hypothesis that treatment with a dipeptidyl peptidase-4 inhibitor initiated soon after a coronary event improves beta-cell function. METHODS: Acute coronary syndrome ACS patients with IGT or T2DM (n = 71), screened by oral glucose tolerance test (OGTT) 4-23 days (median 6 days) after hospital admission, were randomly assigned to sitagliptin 100 mg (n = 34) or placebo (n = 37) and treated for a duration of 12 weeks. All patients received lifestyle advice but no glucose-lowering agents other than the study drug. The study end-point was beta-cell function assessed using the insulinogenic index (IGI = ΔInsulin30 /ΔGlucose30 ), derived from an OGTT, and acute insulin response to glucose (AIRg) assessed by a frequently sampled intravenous glucose tolerance test. RESULTS: The IGI and AIRg did not differ at baseline between the sitagliptin and placebo groups (69.9 vs. 66.4 pmol mmol(-1) and 1394 vs. 1106 pmol L(-1) min(-1) respectively). After 12 weeks, the IGI was 85.0 in the sitagliptin and 58.1 pmol/mmol in the placebo group (P = 0.013) and AIRg was 1909 and 1043 pmol L(-1) min(-1) (P < 0.0001) in the sitagliptin and placebo groups respectively. Fasting glucose at baseline was 6.1 mmol L(-1) in sitagliptin-treated patients and 6.0 mmol L(-1) in those who received placebo compared with 5.8 and 5.9 mmol L(-1) respectively, after 12 weeks of treatment. Post load glucose metabolism improved in significantly more sitagliptin-treated patients compared with the placebo group (P = 0.003). Sitagliptin was well tolerated. CONCLUSION: Sitagliptin improved beta-cell function and glucose perturbations in patients with ACS and newly diagnosed glucose disturbances.

Low serum 25-hydroxyvitamin D level predicts progression to type 2 diabetes in individuals with prediabetes but not with normal glucose tolerance.

AIMS/HYPOTHESIS: Vitamin D deficiency may increase the risk of type 2 diabetes. We therefore investigated whether serum concentrations of 25-hydroxyvitamin D [25(OH)D] would predict the development of prediabetes (impaired fasting glucose, impaired glucose tolerance or the two combined) and type 2 diabetes, either on their own or when combined with serum concentrations of IGF-1 or IGF-binding protein-1 (IGFBP-1), which may interact with 25(OH)D. METHODS: At baseline, participants aged 35-56 years without known type 2 diabetes were examined using OGTTs, 25(OH)D and IGF peptide measurements, and anthropometric and lifestyle data. Participants who had prediabetes or type 2 diabetes at follow-up 8-10 years later were selected as cases; these were then age- and sex-matched to controls with normal glucose tolerance (NGT) at both baseline and follow-up, giving a total of 980 women and 1,398 men. RESULTS: Men but not women in the highest quartile of 25(OH)D level had a decreased OR for developing type 2 diabetes after adjustment for confounders (OR 0.52, 95% CI 0.30, 0.90), an effect accounted for by individuals with prediabetes, but not with NGT, at baseline. In both sexes, progression from prediabetes to type 2 diabetes was reduced by about 25% per 10 nmol/l increase in 25(OH)D. A high IGFBP-1 value was a better predictor of a reduced risk of type 2 diabetes than high 25(OH)D for both sexes, whereas high IGF-1 concentrations predicted a decreased risk only in men. CONCLUSIONS/INTERPRETATION: High serum 25(OH)D concentrations predict a reduced risk of type 2 diabetes in individuals with prediabetes, but not NGT. There were no significant interactions between 25(OH)D and IGFBP-1 or IGF-1 in terms of risk of diabetes. Our data suggest that vitamin D supplementation should be evaluated for the prevention of type 2 diabetes in prediabetic individuals.

Differential incretin effects of GIP and GLP-1 on gastric emptying, appetite, and insulin-glucose homeostasis.

BACKGROUND: Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are major incretins with important effects on glucoregulatory functions. The aim of this study was to investigate effects of GIP and GLP-1 on gastric emptying and appetite after a mixed meal, and effects on insulin secretion and glucose disposal in humans. METHODS: Randomized crossover single-blind study in 17 healthy volunteers receiving GIP (2 or 5 pmol kg(-1) min(-1), n = 8), GLP-1 (0.75 pmol kg(-1) min(-1), n = 9) or NaCl for 180 min with a radionuclide-labeled omelette and fruit punch (370 kcal). Outcome measures were gastric emptying rate, insulinogenic index, hunger, satiety, desire to eat, and prospective food consumption. Blood was analyzed for GIP, GLP-1, glucagon, C-peptide, peptide YY (PYY) and ghrelin. KEY RESULTS: Glucose-dependent insulinotropic polypeptide 2 and 5 pmol kg(-1) min(-1) decreased gastric half-emptying time from 128.5 ± 34.0 min in controls to 93.3 ± 6.3 and 85.2 ± 11.0 min (P < 0.05). Glucose-dependent insulinotropic polypeptide 5 pmol kg(-1) min(-1) decreased postprandial glucose (P < 0.001) and insulin (P < 0.05) with increased insulinogenic index. Glucose-dependent insulinotropic polypeptide had no effects on hunger, desire to eat, satiety or prospective consumption. Glucagon-like peptide-1 0.75 pmol kg(-1) min(-1) increased half-emptying time from 76.6 ± 7.6 min to 329.4 ± 71.6 (P < 0.01). Glucagon-like peptide-1 decreased plasma glucose and insulin (both P < 0.05-0.001), and increased insulinogenic index markedly. Hunger, desire to eat and prospective consumption were decreased (P < 0.05), and satiety borderline increased (P < 0.06). CONCLUSION & INFERENCES: The incretin effect of GIP and GLP-1 differs as GLP-1 exerts a strong glucoregulatory incretin through inhibition of gastric emptying, which GIP does not. Thus, GLP-1 as incretin mimetic may offer unique benefits in terms of weight loss in treatment of type 2 diabetes.

The incretin hormones GIP and GLP-1 in diabetic rats: effects on insulin secretion and small bowel motility.

Incretin hormones often display inhibitory actions on gut motility. The aim of this study was to investigate if altered responsiveness to glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1) as regards insulin release and small bowel motility could bring further clarity to the pathophysiology of diabetes in the Goto-Kakizaki (GK) rat. The isolated perfused pancreas was studied in male GK and Wistar rats (controls) under euglycemic and hyperglycemic conditions. Glucose-dependent insulinotropic peptide (10 nmol L(-1)) or GLP-1 (10 nmol L(-1)) were added to the medium and perfusate was collected and analysed for insulin. Moreover, GK and Wistar rats were supplied with bipolar electrodes in the small bowel and myoelectric activity was recorded during intravenous administration of GIP (1-400 pmol kg(-1) min(-1)) or GLP-1 (0.1-20 pmol kg(-1) min(-1)). Finally, tissue was collected from GK and Wistar rats for RNA extraction. Under euglycemia, GIP and GLP-1 stimulated the initial insulin response by 10-fold in GK rats (P < 0.05). At later hyperglycemia, the insulin response to GIP and GLP-1 was blunted to about one-third compared with controls (P < 0.05). In the bowel GLP-1 was about 2.6-16.7 times more potent than GIP in abolishing the migrating myoelectric complex in the GK and control rats. Polymerase chain reaction (PCR) showed GIP and GLP-1 receptor gene expression in pancreatic islets and in small bowel. The initially high, but later low insulin responsiveness to stimulation with GIP and GLP-1 along with inhibition of small bowel motility in the GK rat indicates a preserved incretin response on motility in diabetes type 2.

Loci of TCF7L2, HHEX and IDE on chromosome 10q and the susceptibility of their genetic polymorphisms to type 2 diabetes.

TCF7L2, HHEX and IDE on chromosome 10q23-25 reside within the linkage region for type 2 diabetes (T2D). Previous studies including ours have demonstrated that genetic polymorphisms in these three loci are associated with T2D, respectively. But, it is unclear whether TCF7L2, independently or interactively with HHEX and IDE, confer the susceptibility to T2D. In the present study, we first replicated genetic association study of the TCF7L2 gene in a Swedish cohort including 528 non-diabetic healthy controls and 243 T2D patients and then evaluated combining effect from common risk polymorphisms in TCF7L2-HHEX-IDE loci. T2D patients were diagnosed in the intermediate study time. To avoid influence from anti-diabetic treatment, baseline data in all T2D patients were used for analysis. We found that SNPs rs7901695, rs4506565, rs7903146 and rs12255372 in the TCF7L2 gene were strongly associated with T2D (p<0.004). In rs7903146, T2D patients carrying genotypes CT or TT had higher fasting plasma glucose (FPG) levels (p=0.042) and lower HOMA-beta index (p=0.015) and BMI (p=0.015) compared to the patients carrying CC genotype. Furthermore, the risk alleles from TCF7L2 rs7903146 polymorphism either with IDE rs2251101 polymorphism (p=0.0257, OR=1.398) or with HHEX rs1544210 polymorphism (p=0.0024, OR=1.514) were significantly associated with T2D. When risk alleles from three loci were combined, the association with T2D remained significant (p=0.0018, OR=1.506). The present study thus provides evidence that TCF7L2, as the main gene, together with HHEX and IDE loci have combining effects on genetic predisposition to T2D.

The estrogen receptor {alpha}-selective agonist propyl pyrazole triol improves glucose tolerance in ob/ob mice; potential molecular mechanisms.

The aim of this study was to validate the role of estrogen receptor alpha (ERalpha) signaling in the regulation of glucose metabolism, and to compare the molecular events upon treatment with the ERalpha-selective agonist propyl pyrazole triol (PPT) or 17beta-estradiol (E(2)) in ob/ob mice. Female ob/ob mice were treated with PPT, E(2) or vehicle for 7 or 30 days. Intraperitoneal glucose and insulin tolerance tests were performed, and insulin secretion was determined from isolated islets. Glucose uptake was assayed in isolated skeletal muscle and adipocytes. Gene expression profiling in the liver was performed using Affymetrix microarrays, and the expression of selected genes was studied by real-time PCR analysis. PPT and E(2) treatment improved glucose tolerance and insulin sensitivity. Fasting blood glucose levels decreased after 30 days of PPT and E(2) treatment. However, PPT and E(2) had no effect on insulin secretion from isolated islets. Basal and insulin-stimulated glucose uptake in skeletal muscle and adipose tissue were similar in PPT and vehicle-treated ob/ob mice. Hepatic lipid content was decreased after E(2) treatment. In the liver, treatment with E(2) and PPT increased and decreased the respective expression levels of the transcription factor signal transducer and activator of transcription 3, and of glucose-6-phosphatase. In summary, our data demonstrate that PPT exerts anti-diabetic effects, and these effects are mediated via ERalpha.

Psychological distress and risk of pre-diabetes and Type 2 diabetes in a prospective study of Swedish middle-aged men and women.

AIMS: To determine the role of psychological distress as a predictor of pre-diabetes and Type 2 diabetes. METHODS: This cohort study comprised 2127 Swedish middle-aged men and 3100 women with baseline normal glucose tolerance measured by oral glucose tolerance test. At follow-up 8-10 years later, 245 men and 177 women had pre-diabetes [impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and IFG + IGT] and Type 2 diabetes was detected in 103 men and 57 women. Baseline psychological distress was measured by an index of five questions concerning anxiety, apathy, depression, fatigue and insomnia. Odds ratios (ORs) were estimated for pre-diabetes and Type 2 diabetes in association with total psychological distress. In addition, ORs of the single-item questions were calculated. RESULTS: In men, adjusted ORs (95% confidence interval) in the highest index group of psychological distress compared with the lowest group were 1.9 (1.2-2.8) and 2.2 (1.2-4.1) for pre-diabetes and Type 2 diabetes, respectively. Corresponding estimates in women were 1.2 (0.7-2.1) and 0.5 (0.2-1.2). In the middle symptoms groups, adjusted ORs in men were 1.1 (0.8-1.4) for pre-diabetes and 1.2 (0.7-2.0) for Type 2 diabetes and in women 1.8 (1.1-3.0) and 0.7 (0.3-1.4). When analysed separately, the associations with each of the five single factors were similar. CONCLUSIONS: The results indicate that psychological distress, including symptoms of anxiety, apathy, depression, fatigue and insomnia, increases the risk of pre-diabetes and Type 2 diabetes in Swedish middle-aged men. Increased risks were not present in women, except for pre-diabetes in the middle index group.

Insulin-like growth factor-binding protein-1 in the prediction and development of type 2 diabetes in middle-aged Swedish men.

AIMS/HYPOTHESIS: Insulin-like growth factor-binding protein-1 (IGFBP-1) production in the liver is inhibited by insulin, and low circulating levels are associated with the metabolic syndrome. The aim of this study was to evaluate the predictive role and change in IGFBP-1 concentrations during development of abnormal glucose regulation. METHODS: IGFBP-1 levels were determined at baseline and at 10 years in an incident case-control prospective study of Swedish white men aged 35-56 years. Individuals with normal glucose tolerance at baseline who developed abnormal glucose tolerance during a 10 year period (n = 355) according to WHO criteria were pair-matched to controls for age and family history of diabetes. RESULTS: Fasting IGFBP-1 concentrations were lower in individuals who later developed abnormal glucose regulation and correlated inversely with fasting proinsulin values (r = -0.48; p < 0.0001), and both were significant predictors. Individuals in the highest quartile at baseline for an algorithm incorporating fasting IGFBP-1, blood glucose, proinsulin and waist and height had a 40-fold increased risk of developing type 2 diabetes compared with the lowest quartile (95% CI 7.7-214). IGFBP-1 increased 32% (95% CI 17-49%) during the 10 years in those developing diabetes and was increased in relation to insulin levels, suggesting the emergence of hepatic insulin resistance. Moreover, elevated IGFBP-1 levels at follow-up were associated with higher 2 h glucose values during an OGTT. CONCLUSIONS/INTERPRETATION: Low IGFBP-1 predicts the development of abnormal glucose regulation and, as an inhibitor of the insulin-like actions of insulin-like growth factors, elevated levels of IGFBP-1 after the development of diabetes may also play a pathophysiological role.

Contribution of gluconeogenesis and glycogenolysis to hepatic glucose production in acromegaly before and after pituitary microsurgery.

The diabetogenic effect of excess growth hormone (GH) such as that in acromegaly is well known. However, the contribution of the various components to hepatic glucose production (HGP) is not completely understood. In this study we evaluated insulin resistance, HGP, gluconeogenesis (GNG), and glycogenolysis (GLY) in five patients with acromegaly before and after pituitary microsurgery. Insulin resistance was estimated by the HOMA index. HGP was measured using a primed continuous (6,6- 2H2) glucose infusion, and GNG was measured from 2 H enrichment at carbons 2 and 5 of blood glucose on ingestion of 2H2O. The ratio of these enrichments equals the fractional contribution of GNG to HGP, and GLY was calculated as the difference between HGP and GNG. All measurements were performed after 12 hours of fasting. Levels of GH and IGF-I decreased, as did the HOMA index (p<0.05). HGP was reduced from 11.4 micromol/kg/min to 9.7 micromol/kg/min (p=0.032). GNG contributed most to HGP. GNG was unchanged, whereas GLY's fraction decreased 29% (p=0.056) postoperatively. This pilot study indicates that GNG is the main contributor to HGP and that GLY is more sensitive than is GNG to the insulin resistance existing in acromegaly.

Insulin glargine improves glycaemic control after coronary surgery in patients with diabetes or pre-diabetes.

OBJECTIVES: Determine if pre-emptive daily insulin glargine surpasses regular insulin when needed for glycaemic control after cardiac surgery. DESIGN: Prospective, randomized study of 43 patients (scheduled for coronary artery bypass grafting) with preoperatively diagnosed diabetes (DM) or pre-DM. Lantus group received insulin glargine daily from start of surgery while Actrapid group received regular insulin (sliding scale) when needed (plasma glucose (P-glu)>10 mmol/l). Primary endpoint was percent of pre- and post-prandial P-glu values within Target Intervals: Pre-prandial P-glu: 4.5-7 mmol/l; post-prandial P-glu: 4.5-9 mmol/l. Study period 1-4 days after surgery. Tissue glucose was also measured continuously. RESULTS: More than twice as many P-glu values were within Target Interval for Lantus patients as compared with Actrapid patients (p<0.001). One of 504 timed measurements was <4 mmol/l. Area under the curve for glucose>7 mmol/l was reduced by 61% by Lantus (p<0.001). CONCLUSION: The routine protocol with pre-emptive glargine insulin studied here provides a major improvement in glycaemic control with a minimal incidence of hypoglycaemia and without an excessive increase in nursing burden.

GLP-1 suppresses gastrointestinal motility and inhibits the migrating motor complex in healthy subjects and patients with irritable bowel syndrome.

Glucagon-like peptide-1 (GLP-1) is released after food intake to act as an incretin. GLP-1 also inhibits gastric emptying and increases satiety. In rats, GLP-1 inhibits small bowel motility. Our aim was to study the effects of GLP-1 on gastrointestinal motility in healthy subjects and patients with irritable bowel syndrome (IBS). Antro-duodeno-jejunal manometry was carried out during a 4-h control period with saline, followed by a 4-h period with intravenous GLP-1 (healthy: 0.7 and 1.2 pmol kg(-1) min(-1) (n = 16); IBS, 1.2 and 2.5 pmol kg(-1) min(-1) (n = 14). Plasma was analysed for GLP-1 and gut hormones, and gut tissue expression of GLP-1 receptor was studied. In healthy subjects, GLP-1 0.7 pmol kg(-1) min(-1) reduced the migrating motor complexes (MMCs) from a median of 2 (range 2-3) to 0.5 (0-2), and motility index from 4.9 +/- 0.1 to 4.3 +/- 0.3 ln Sigma(mmHg*s min(-1)) in jejunum, while GLP-1 1.2 pmol kg(-1) min(-1) diminished MMCs from 2 (2-3) to 1.5 (1-2.5), and motility index from 5.2 +/- 0.2 to 4.4 +/- 0.2. In IBS patients, GLP-1 1.2 pmol kg(-1) min(-1) reduced the MMCs from 2.5 (2-3.5) to 1 (0-1.5) without affecting motility index. At 2.5 pmol kg(-1) min(-1) GLP-1 decreased MMCs from 2 (1.5-3) to 1 (0.5-1.5), and motility index from 5.2 +/- 0.2 to 4.0 +/- 0.5. Motility responses to GLP-1 were similar in antrum and duodenum. Presence of the GLP-1 receptor in the gut was verified by reverse transcriptase PCR. In conclusion, the gut peptide GLP-1 decreases motility in the antro-duodeno-jejunal region and inhibits the MMC in healthy subjects and IBS patients.

Pathophysiology and treatment of patients with type 2 diabetes exhibiting failure to oral drugs.

It is generally accepted that a poor glycaemic control increases the risk for development of vascular complications in diabetic patients. This advocates for early introduction of insulin treatment in patients with type 2 diabetes exhibiting a secondary failure to oral treatment. This strategy is facilitated by introduction of long-acting insulin glargine and biphasic insulin aspart 70/30. The introduction of Glucagon-like peptide-1 (GLP-1) mimetics and dipeptidyl peptidase 4 (DPP-4) inhibitors in treatment of type 2 diabetes will however, to a large extent, influence therapeutic policy. Thus we suggest that DPP-4 inhibitors or long-acting GLP-1 mimetics will be used as either first-line therapy or as an early addition to metformin. The already generated results in animal and clinical studies suggest that these two classes of antidiabetic drugs may in addition to improving glycaemic control protect islet beta-cell mass and thereby postpone development of a secondary failure. When patients treated with metformin, sulfonylurea (SU), tiazolidinediones or a combination of these drugs fail, the GLP-1 mimectics may be preferred to insulin treatment. First, the risk of hypoglycaemia is less if not combined with SU. Secondly, the body weight is usually decreased while insulin treatment increases weight. Patients not responding to GLP-1 mimetics or experiencing significant side effects will be treated with insulin. Irrespective of the policy used for the drug treatment of type 2 diabetes, exercise and proper diet will remain important for optimization of metabolic control.

Genetic variation of the adenylyl cyclase 3 (AC3) locus and its influence on type 2 diabetes and obesity susceptibility in Swedish men.

OBJECTIVE: Our previous study using the Goto-Kakizaki rat implicates that the adenylyl cyclase 3 (AC3) is a candidate gene for genetic study of metabolic disorders. The present study aimed to investigate the susceptibility of genetic variation of the AC3 gene in type 2 diabetes (T2D) patients and obese subjects. SUBJECTS AND METHODS: Variation screening in the putative promoter and validation of single nucleotide polymorphisms (SNPs) covering the AC3 gene were performed. In total, 630 Swedish men, including 243 T2D patients (BMI from 18.4 to 45.6 kg m(-2)), 199 obese subjects with normal glucose tolerance (NGT, BMI> or =30 kg m(-2)) and 188 control subjects (NGT, BMI< or =26 kg m(-2)), were genotyped. RESULTS: A novel variant -17A/T in the promoter was identified, but no significant association of this polymorphism with T2D was found. SNPs rs2033655 C/T and rs1968482 A/G were found to be significantly associated with obesity when T2D patients had BMI> or =30 kg m(-2) (P=0.003 and 0.005). The significance was borderline in T2D patients with BMI<30 kg m(-2) (P=0.051 and 0.084) and disappeared in T2D patients with BMI< or =26 kg m(-2). Importantly, analysis in obese subjects with NGT demonstrated that these two polymorphisms were strongly associated with obesity per se (P=0.028 and 0.003). Furthermore, analyses for diplotypes (haplotypic genotypes) predicted an association with BMI in obese subjects. CONCLUSIONS: The present study provides the first evidence that AC3 polymorphisms confer the risk susceptibility to obesity in Swedish men with and without type 2 diabetes.

Islet gene expression and function in type 2 diabetes; studies in the Goto-Kakizaki rat and humans.

Defective beta-cell function with resulting impairment of glucose-stimulated insulin release is a critical factor in the pathogenesis of type 2 diabetes. Accumulated studies in pancreatic islets of the spontaneously diabetic Goto-Kakizaki (GK) rat suggest that this is a useful animal model of type 2 diabetes. The GK rat is non-obese, and abnormal glucose regulation develops early in life in association with impaired insulin secretion. There are some differences in islet morphology and function reported between different GK rat colonies. In addition to reduction of beta-cell mass, a number of beta-cell defects have been described with possible relevance for the reduced insulin secretion. Interestingly, some of these defects have also been shown in isolated islets from type 2 diabetic humans. The polygenic nature of diabetes heredity in the GK rat may well resemble the genetic basis in the majority of patients with type 2 diabetes. Here, we review studies concerning beta-cell function and islet gene expression in the GK rat and compare it with the limited number of investigations on similar topics in isolated islets from patients with type 2 diabetes.

Arachidonic acid signaling is involved in the mechanism of imidazoline-induced KATP channel-independent stimulation of insulin secretion.

The mechanism by which the novel, pure glucose-dependent insulinotropic, imidazoline derivative BL11282 promotes insulin secretion in pancreatic islets has been investigated. The roles of KATP channels, alpha2-adrenoreceptors, the I1-receptor-phosphatidylcholine-specific phospholipase (PC-PLC) pathway and arachidonic acid signaling in BL11282 potentiation of insulin secretion in pancreatic islets were studied. Using SUR1(-/-) deficient mice, the previous notion that the insulinotropic activity of BL11282 is not related to its interaction with KATP channels was confirmed. Insulinotropic activity of BL11282 was not related to its effect on alpha2-adrenoreceptors, I1-imidazoline receptors or PC-PLC. BL11282 significantly increased [3H]arachidonic acid production. This effect was abolished in the presence of the iPLA2 inhibitor, bromoenol lactone. The data suggest that potentiation of glucose-induced insulin release by BL11282, which is independent of concomitant changes in cytoplasmic free Ca2+ concentration, involves release of arachidonic acid by iPLA2 and its metabolism to epoxyeicosatrienoic acids through the cytochrome P-450 pathway.

GHR exon 3 polymorphism: association with type 2 diabetes mellitus and metabolic disorder.

Growth hormone (GH) signaling via the growth hormone receptor (GHR) forms a major part of the GH-IGF-I axis, which is crucial for controlling metabolism and anabolism. Two common variants of the GHR differ by the presence (full length or GHR(fl)) or absence of exon 3 (exon 3 deleted or GHR(d3)), the function of which is unknown. However, differential response to GH treatment has been observed with carriers of the GHR(d3) variant conferring a greater growth rate. This study investigates these GHR variants in subjects with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT), including Type 2 diabetes mellitus (T2DM). DNA was extracted from blood samples from subjects with NGT (n=158), IGT (n=116) and T2DM (n=194). The T2DM subjects in set 1 (n= 39) were newly diagnosed, whilst those in set 2 (n=155) had a mean duration of 7 years. Set 1 also included NGT and IGT subjects. Genotyping by standard PCR and gel electrophoresis were carried out. A significant difference was observed between T2DM and NGT (p<0.0001) with a significantly lower frequency of GHR(d3) in T2DM (3.6% compared to 17% in NGT). Both sets of T2DM subjects with at least one GHR(d3) allele had significantly higher BMI. In the larger subset of T2DM, GHR(d3) was associated with higher CRP levels as well as age adjusted IGF-I, with a trend of higher C-peptide secretion and impaired lipid levels, indicating a phenotype with metabolic disorder when compared to the GHR(fl/fl) T2DM subjects. In conclusion, homozygosity for the GHR(d3) allele appears to be preventive of T2DM. However, when other factors cause overt T2DM, the GHR(d3) allele confers a phenotype indicative of metabolic disorder. This study supports the hypothesis that the two GHR alleles by their inclusion or exclusion of exon 3 are functionally different.

Socio-economic position at three points in life in association with type 2 diabetes and impaired glucose tolerance in middle-aged Swedish men and women.

BACKGROUND: It has been suggested that low socio-economic position (SEP) during childhood and adolescence predicts risk of adult type 2 diabetes. We investigated the associations between type 2 diabetes and childhood SEP (fathers' occupational position), participants' education and adult SEP (participants' occupational position). To determine possible independent associations between early SEP (fathers' occupational position and participants' education) and disease, we adjusted for adult SEP and factors present in adult life associated with type 2 diabetes. METHODS: This cross-sectional study comprised 3128 men and 4821 women aged 35-56 years. All subjects have gone through a health examination and answered a questionnaire on lifestyle factors. At the health centre, an oral glucose tolerance test was administered and identified 55 men and 52 women with previously undiagnosed type 2 diabetes. Relative risks (RRs) with 95% CIs were calculated in multiple logistic regression analyses. RESULTS: The age-adjusted RRs of type 2 diabetes if having a father with middle occupational position were 2.3 [Confidence interval (CI:1.0-5.1) for women and, 2.0 (CI:0.7-5.6) for men]. Moreover, low education was associated with type 2 diabetes in women, RR = 2.5 (CI:1.2-4.9). Low occupational position in adulthood was associated with type 2 diabetes in women, RR = 2.7 (CI:1.3-5.9) and men, RR = 2.9 (CI:1.5-5.7). The associations between early SEP and type 2 diabetes disappeared after adjustment for adult SEP and factors associated with type 2 diabetes. CONCLUSION: The association between type 2 diabetes and low SEP during childhood and adolescence in middle-aged Swedish subjects disappeared after adjustment for adult SEP and adult risk factors of diabetes.

Differential protein expression in pancreatic islets after treatment with an imidazoline compound.

The effects of an imidazoline compound (BL11282) on protein expression in rat pancreatic islets were investigated with a proteomic approach. The compound increases insulin release selectively at high glucose concentrations and is therefore of interest in type 2 diabetes. Whole cell extracts from isolated drug-treated and native pancreatic rat islets were compared after separation by 2-D gel electrophoresis. Differentially expressed proteins were identified by mass spectrometry; 15 proteins were selectively up-regulated and 7 selectively down-regulated in drug-treated islets. Of special interest among the differentially expressed proteins are those involved in protein folding (Hsp60, protein disulfide isomerase, calreticulin), Ca(2+) binding (calgizzarin, calcyclin and annexin I) and metabolism or signalling (pyruvate kinase, alpha enolase and protein kinase C inhibitor 1).