Effect of different fibers on glucose and lipid levels in diabetic subjects

The diabetic diet has traditionally been low in carbohydrate content. However, recent studies have shown that the diet may be liberalized in this respect provided that complex carbohydrates are given. When given in amounts corresponding to 50 g starch beans, in particular, raise the blood glucose levels to only a small extent and less than various other foodstuffs tested. The reason for this is, at least in part, due to the effect of the constituent fibers. Guar is another fiber of bean origin which has been shown to lower the postprandial glucose levels. Data from long-term treatment of diabetic patients with guar are presented.

Differences in metabolic responses to beta-adrenergic stimulation after propranolol or metoprolol administration

Isoprenaline, or the beta 2-agonist terbutaline, was infused in healthy male volunteers and the plasma levels of insulin, glucose and free fatty acids (FFA) were determined. Saline, propranolol, or the selective beta 1-receptor antagonist, metoprolol, was administered i.v. prior to the infusion of the beta-stimulants. The two beta-receptor blockers inhibited isoprenaline-induced increase in chronotropy to about the same extent, while the effects on systolic and diastolic blood pressure were in accordance with a selective beta1-blocking effect of metoprolol and a non-selective beta-blocking action of propranolol. Quantitative differences were found between metoprolol and propranolol on the metabolic parameters. The effects can best be described in terms of beta 1- or beta 2-receptors, where effects on plasma FFA and glycerol levels seem to be mainly beta1-mediated. An apparent beta 2-mediated effect was found for insulin release and hepatic glucose output.

Cells in human adipose tissue developing into adipocytes

Sedimentable cells from human adipose tissue of different origins were cultured under conditions when cell multiplication was prevented but lipid filling optimized (suspension culture). In this way an estimation was obtained of the number of in vivo determined adipose precursor cells (preadipocytes) which were not filled with lipid. Under these conditions no cells from adult, non-obese subjects developed to adipocytes. Cells developing to adipocytes constituted less than 0.02% and 1% of adipocytes in tissues from obese adults and from children, respectively. It was concluded that in vivo determined adipocyte precursor cells (preadipocytes, lipid-free fat cells) are not present in a significant number in human adipose tissue either from adults or from children as tested with the method employed, allowing detection of a large number of such cells in adipose tissue from small rats.

Relation between ST-depression and chest pain in patients with coronary heart disease receiving no treatment and after beta-blockade and combined alpha-beta-blockade

The bicycle exercise tolerance was studied in ten patients with angina pectoris after one week's treatment with an alpha-beta-blocker (labetalol 300 mg b.d.), alpha-beta-blocker (propranolol 80 mg b.d.) and placebo. The ST-segment of the ECG was continuously evaluated by on-line computerized averaging of complexes which greatly reduces noise and eliminate artefacts caused by varying baseline. Blood pressure was lowest with labetalol and heart rate lowest with labetalol and of heart rate during exercise was equally well depressed by both drugs. They also attenuated ST-depression at a given load but enhanced ST-depression for a given heart rate. At heart rate 100/min ST-depression was significantly greater with propranolol than with labetalol. It is concluded that provided ST-depression during treatment with B-blockers is correlated to myocardial ischemia in the same way as without such treatments used, other factors, e.g. an increase in cardiac size, will contribute more to the ischemia. labetalol may cause less increase in cardiac size than propranolol.

The effect of beta-blockade on glucose tolerance and insulin release in adult diabetes

Blood glucose and plasma insulin levels were studied in ten adult diabetics treated in a cross-over fashion for at least three weeks with alprenolol, a non-selective beta-blocker, or with metoprolol, a cardioselective beta 1-blocker. Dietary intake was controlled three days prior to the study which comprised both i.v. and oral glucose tolerance tests. Mean fasting blood glucose levels were significantly higher on alprenolol than on metoprolol. The increase in fasting blood glucose was particularly pronounced in two patients. In these subjects the glucose tolerance following both an i.v. and an oral glucose load was reduced when treatment was switched from metoprolol to alprenolol. Lower plasma insulin levels in response to glucose were also found in these patients on alprenolol than on metoprolol. The mean insulin levels for all ten patients did not differ significantly between the two treatment periods. These data show that treatment with a non-selective beta-blocker can in some patients cause a considerable deterioration of the glucose tolerance, presumably due to inhibition of insulin release.

Adrenergic control of lipid metabolism

Adrenergic receptors are ubiquitous and mediate several important effects involving lipid metabolism. Thus, beta-adrenergic stimulation increases lipolysis and inhibits the activity of the lipoprotein lipase. In contrast, alpha-adrenergic stimulation inhibits fat cell lipid mobilisation. Unexpectedly, beta-adrenergic blockade increases plasma triglyceride levels and tends to lower the high density lipoprotein (HDL-cholesterol). These effects seem to be prevented or attenuated by concomitant alpha-blockade. Possible mechanisms for the adrenergic effect on lipid metabolism are reviewed.

Insulin and free oestradiol are independent risk factors for benign prostatic hyperplasia

The aetiology of benign prostatic hyperplasia (BPH) remains unclear. The objective of the present study was to test the insulin, oestradiol and metabolic syndrome hypotheses as promoters of BPH. The design was a risk factor analysis of BPH in which the total prostate gland volume was related to endocrine and anthropometric factors. The participants studied were 184 representative men, aged 72-76 years, residing in Göteborg, Sweden. Using a multivariate analysis, BPH as measured by the total prostate gland volume correlated statistically significantly with fasting serum insulin (beta=0.200, P=0.028), free oestradiol (beta=0.233, P=0.008) and lean body mass (beta=0.257, P=0.034). Insulin and free oestradiol appear to be independent risk factors for BPH, confirming both the insulin and the oestradiol hypotheses. Our findings also seem to confirm the metabolic syndrome hypothesis. The metabolic syndrome and its major endocrine aberration, hyperinsulinaemia, are possible primary events in BPH.

Overexpression of Il6 leads to hyperinsulinaemia, liver inflammation and reduced body weight in mice

AIMS/HYPOTHESIS

IL-6 is released by the adipose tissue and increased circulating levels in obesity are associated with hyperinsulinaemia and insulin resistance. Short-term experiments suggest that increased IL-6 release by the skeletal muscle following exercise may improve insulin sensitivity.

METHODS

In order to examine the effect of chronically elevated IL-6 levels, we overexpressed Il6 in skeletal muscle in mice using an electro-transfer procedure.

RESULTS

Circulating IL-6 levels were increased and the animals rapidly lost both weight and body fat, but food intake was unchanged, which is consistent with the finding that IL-6 increased energy expenditure. Insulin levels were inappropriately elevated and combined with hypoglycaemia in spite of reduced 2-deoxy-D: -glucose uptake by skeletal muscle. Insulin-stimulated glucose uptake by skeletal muscles ex vivo was reduced, probably due to the decreased amounts of glucose transporter (GLUT)-4. Beta cell insulin content was increased, while apparent beta cell mass was unchanged. Circulating serum amyloid A cluster levels were increased tenfold due to a pronounced proinflammatory state in the liver with infiltration of inflammatory cells. However, no liver steatosis was found, which may be accounted for by concomitant AMP kinase activation.

CONCLUSIONS/INTERPRETATION

Chronically elevated IL-6 levels lead to inappropriate hyperinsulinaemia, reduced body weight, impaired insulin-stimulated glucose uptake by the skeletal muscles and marked inflammation in the liver. Thus, the pleiotrophic effects of chronically elevated IL-6 levels preclude any obvious usefulness in treating obesity or its associated metabolic complications in man, despite the fact that weight reduction may be expected.

The common SLC30A8 Arg325Trp variant is associated with reduced first-phase insulin release in 846 non-diabetic offspring of type 2 diabetes patients--the EUGENE2 study

AIMS/HYPOTHESIS

A recent genome-wide association study identified the SLC30A8 rs13266634 polymorphism encoding an Arg325Trp polymorphism in the zinc transporter protein member 8 (ZnT-8) to be associated with type 2 diabetes. Here, we investigate whether the polymorphism is related to altered insulin release in response to intravenous and oral glucose loads in non-diabetic offspring of type 2 diabetic patients.

METHODS

We genotyped SLC30A8 rs13266634 in 846 non-diabetic offspring of type 2 diabetic patients from five different white populations: Danish (n = 271), Finnish (n = 217), German (n = 149), Italian (n = 109) and Swedish (n = 100). Participants were subjected to both IVGTTs and OGTTs, and measurements of insulin sensitivity.

RESULTS

Homozygous carriers of the major type 2 diabetes C risk-allele showed a 19% decrease in first-phase insulin release (0-10 min) measured during the IVGTT (CC 3,624 +/- 3,197; CT 3,763 +/- 2,674; TT 4,478 +/- 3,032 pmol l(-1) min(-1), mean +/- SD; p = 0.007). We found no significant genotype effect on insulin release measured during the OGTT or on estimates of insulin sensitivity.

CONCLUSIONS/INTERPRETATION

Of European non-diabetic offspring of type 2 diabetes patients, 46% are homozygous carriers of the Arg325Trp polymorphism in ZnT-8, which is known to associate with type 2 diabetes. These diabetes-prone offspring are characterised by a 19% decrease in first-phase insulin release following an intravenous glucose load, suggesting a role for this variant in the pathogenesis of pancreatic beta cell dysfunction.

High circulating levels of RBP4 and mRNA levels of aP2, PGC-1alpha and UCP-2 predict improvement in insulin sensitivity following pioglitazone treatment of drug-naïve type 2 diabetic subjects

CONTEXT

High levels of circulating retinol-binding protein 4 (RBP4) and baseline expression of adipogenic genes correlate with subsequent improvement in insulin sensitivity following Thiazolidinedione (TZD) treatment.

OBJECTIVE

The aim was to identify baseline characteristics and early changes related to TZD treatment that could predict a good treatment response.

DESIGN

Subjects were examined with oral glucose tolerance test, intravenous glucose tolerance test, hyperinsulinaemic euglycaemic clamp, body composition and standard blood sampling at baseline and after 4 and 12 weeks treatment. Subcutaneous adipose tissue biopsies were taken from the abdominal region at baseline, after 3 days and 4 weeks treatment to examine the gene expression profile.

SETTING

Research laboratory in a University hospital.

PARTICIPANTS

Ten newly diagnosed and previously untreated type 2 diabetic subjects were treated with pioglitazone for 3 months.

MAIN OUTCOME MEASURES

Baseline characteristics and early changes related to TZD treatment that could predict the response after 3 months.

RESULTS

Pioglitazone improved insulin sensitivity after 4 weeks combined with lower glucose and insulin levels without any change in BMI. It was accompanied by lower circulating resistin and plasminogen activator inhibitor-1 levels rapidly increased levels of circulating total and high molecular weight adiponectin as well as adiponectin and adipocyte fatty acid-binding protein (aP2) mRNA expression in the adipose tissue. High levels of circulating RBP4 at baseline and adipose tissue expression of aP2, proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1alpha) and uncoupling protein 2 (UCP-2) predicted a good treatment response measured as improvement in insulin-stimulated whole-body glucose uptake after 3 months.

CONCLUSIONS

Circulating levels of RBP4 as an index of insulin sensitivity and mRNA levels of adipogenic genes correlate with the subsequent improvement in insulin sensitivity following TZD treatment.

Insulin sensitivity, insulin release and glucagon-like peptide-1 levels in persons with impaired fasting glucose and/or impaired glucose tolerance in the EUGENE2 study

AIMS/HYPOTHESIS

We examined the phenotype of individuals with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) with regard to insulin release and insulin resistance.

METHODS

Non-diabetic offspring (n=874; mean age 40+/-10.4 years; BMI 26.6+/-4.9 kg/m(2)) of type 2 diabetic patients from five different European Centres (Denmark, Finland, Germany, Italy and Sweden) were examined with regard to insulin sensitivity (euglycaemic clamps), insulin release (IVGTT) and glucose tolerance (OGTT). The levels of glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) were measured during the OGTT in 278 individuals.

RESULTS

Normal glucose tolerance was found in 634 participants, while 110 had isolated IFG, 86 had isolated IGT and 44 had both IFG and IGT, i.e. about 28% had a form of reduced glucose tolerance. Participants with isolated IFG had lower glucose-corrected first-phase (0-10 min) and higher second-phase insulin release (10-60 min) during the IVGTT, while insulin sensitivity was reduced in all groups with abnormal glucose tolerance. Similarly, GLP-1 but not GIP levels were reduced in individuals with abnormal glucose tolerance.

CONCLUSIONS/INTERPRETATION

The primary mechanism leading to hyperglycaemia in participants with isolated IFG is likely to be impaired basal and first-phase insulin secretion, whereas in isolated IGT the primary mechanism leading to postglucose load hyperglycaemia is insulin resistance. Reduced GLP-1 levels were seen in all groups with abnormal glucose tolerance and were unrelated to the insulin release pattern during an IVGTT.

Insulin differentially modulates the peripheral endocannabinoid system in human subcutaneous abdominal adipose tissue from lean and obese individuals

Human obesity has been associated with a dysregulation of the peripheral and adipose tissue (AT) endocannabinoid system (ES). The aim of this study was to elucidate the acute in vivo effects of insulin on gene expression of the cannabinoid type 1 (CB-1) and type 2 (CB-2) receptors, as well as of the fatty acid amide hydrolase (FAAH) in the sc abdominal adipose tissue (SCAAT). Nine lean (L) and 9 obese (OB), but otherwise healthy males were studied in the fasting state and during a euglycemic hyperinsulinemic clamp (40 mU/m2 * min(-1)). SCAAT biopsies were obtained at baseline and after 270 min of i.v. maintained hyperinsulinemia. The basal SCAAT gene expression pattern revealed an upregulation of the FAAH in the OB (p=0.03 vs L), whereas similar CB-1 and CB-2 mRNA levels were seen. Following hyperinsulinemia, the FAAH mRNA levels significantly increased approximately 2-fold in the L (p=0.01 vs baseline) but not in the OB. In contrast, insulin failed to significantly change both the adipose CB-1 and CB-2 gene expression. Finally, the FAAH gene expression positively correlated with the fasting serum insulin concentration (r 0.66; p=0.01), whereas an inverse association with the whole-body glucose disposal (r -0.58; p<0.05) was seen. Taken together, these first time observations demonstrate that the ES-related genes in the SCAAT differentially respond to hyperinsulinemia in lean/insulin-sensitive and in obese/insulin-resistant individuals. We suggest that insulin may play a key role in the obesity-linked dysregulation of the adipose ES at the gene level.

Adipose tissue distribution and risk of metabolic disease: does thiazolidinedione-induced adipose tissue redistribution provide a clue to the answer?

The relative effect of visceral and subcutaneous obesity on the risk of chronic metabolic disease has been a matter of long-term dispute. While ample data support either of the fat depots being causative or associative, valid argument for one depot often automatically belittles the other. Paradigms such as the visceral/portal hypothesis and the acquired lipodystrophy/ectopic fat storage and endocrine hypothesis have been proposed. Nevertheless, neither hypothesis alone explains the entire pathophysiological setting. Treatment of diabetes with thiazolidinediones selectively increases fat partitioning to the subcutaneous adipose depot but does not change visceral fat accumulation. This is in contrast to the preferential visceral fat mobilisation by diet and exercise. Surgical removal of visceral or subcutaneous adipose tissue yields relatively long-lasting metabolic improvement only when combined with procedures that ameliorate adipose tissue cell composition. These studies illustrate that human adipose tissue in different anatomic locations does not work in isolation, and that there is a best-fit relationship in terms of volume and function among different fat depots that needs to be met to maintain the systemic energy balance and to prevent the complications related to obesity.

Weight loss and metabolic effects of topiramate in overweight and obese type 2 diabetic patients: randomized double-blind placebo-controlled trial

OBJECTIVE

To examine the metabolic effects and body composition changes after topiramate treatment of obese type 2 diabetic patients (DM2) for 11 months.

DESIGN AND SUBJECTS

Thirty-eight DM2 on diet or sulfonylurea treatment participated in this randomized double-blind placebo-controlled trial. Thirteen placebo-treated and nine topiramate-treated patients completed the trial. Patients were randomized to treatment with topiramate 96 mg b.i.d. or placebo (6-week run-in phase, 2-months titration phase, 9-months maintenance phase).

MEASUREMENTS

Insulin sensitivity was measured with euglycaemic hyperinsulinemic clamps. Weight, HbA1c, fasting glucose, blood lipids and safety variables were measured at regular intervals. Body composition was determined with computerized tomography. Meal tests were performed to evaluate postprandial glucose and insulin levels. Three-day diet recalls were carried out to evaluate energy ingestion.

RESULTS

The mean age was 58.6+/-7.1 years, body weight 98.1+/-16.1 kg, BMI 33.0+/-4.5 kg/m(2), and glycosylated hemoglobin (HbA1c) 7.3+/-0.9%. In topiramate-treated patients, there were significant reductions in HbA1c (1.1+/-0.9%), fasting plasma glucose, body weight (-6.6+/-3.3%), as well as body fat, lean body mass, postprandial glucose and free fatty acid levels but there were no significant changes in insulin sensitivity. The daily average energy intake decreased more in the topiramate group than in the placebo group. Paresthesia and central nervous system-related side effects were the main causes for the dropout rate.

CONCLUSIONS

Topiramate treatment of overweight DM2 reduced body weight and body fat, and was associated with a marked improvement in glycaemic control whereas no significant improvement in insulin-stimulated glucose uptake was demonstrated. Further studies are required to clarify whether this effect might occur through changes in insulin sensitivity in the liver and/or pancreatic insulin secretion.

Pathogenesis and treatment of diabetic vascular disease - illustrated by two cases

This publication is a summary of the presentations given at the First JIM Grand Round held at the Sahlgrenska University Hospital on 15 March 2006. The Grand Round was based on two case reports; a patient with type 2 diabetes and pronounced macrovascular disease and another patient with early microvascular disease combined with the macrovascular complications. The pathogenesis of the vascular complications and the current treatment regimens were discussed in relation to the history and examinations performed in these patients.

Postprandial interstitial insulin concentrations in type 2 diabetes relatives

BACKGROUND

An endothelial barrier for the insulin transport from the circulation to the target tissues of insulin has previously been suggested to contribute to insulin resistance. The interstitial insulin concentration (I-insulin) and insulin kinetics following a mixed meal have, however, previously not been characterized in human adipose tissue.

SUBJECTS AND METHODS

Eight nondiabetic first-degree relatives (FDR) of type 2 diabetes patients were recruited. Their I-insulin was measured by microdialysis after a test meal with or without oral administration of the insulin secretagogue nateglinide (120 mg). In parallel, adipose tissue blood flow and lipolysis were measured by xenon-clearance and microdialysis, respectively.

RESULTS

The I-insulin increased after the test meal, and this response was more prominent on the day the subjects received the nateglinide tablet when compared with the day the subjects received the placebo tablet [I-insulin incremental area under the curve (IAUC) nateglinide 7612 +/- 3032 vs. Plac 4682 +/- 2613 pmol L(-1) min; P < 0.05, mean +/- SE]. However, the postprandial I-insulin(max)/P-insulin(max) ratio was similar on the two test days (nateglinide: 213 +/- 62 vs. 501 +/- 92 pmol L(-1), I/P-ratio: 0.38 +/- 0.06 and placebo: 159 +/- 39 vs. 410 +/- 74 pmol L(-1), I/P-ratio: 0.36 +/- 0.05). There was no difference in time of onset of insulin action in situ, or responsiveness, when comparing placebo and nateglinide.

CONCLUSIONS

Microdialysis can now be used to measure the I-insulin in human adipose tissue following a mixed meal. The data also showed that the transendothelial delivery of insulin occurs rapidly, supporting the concept that transcapillary insulin transfer is a nonsaturable process in nondiabetic first-degree relatives of type 2 diabetes patients.

Increased levels of acylation-stimulating protein in interleukin-6-deficient (IL-6(-/-)) mice

IL-6-deficient (IL-6(-/-)) mice develop obesity at 6-7 months of age. To elucidate the mechanisms of this mature-onset obesity, global gene expression profiles of 3-month-old preobese IL-6(-/-) were compared with those of IL-6(+/+) mice using DNA arrays. Genes that were up-regulated in IL-6(-/-) mice included the factors transthyretin and properdin in white adipose tissue and adipsin in muscle. These factors have been shown to influence the formation of acylation-stimulating protein (ASP), a cleavage product of complement C3. ASP stimulates the synthesis of triacylglycerol in adipocytes, and ASP-deficient mice are resistant to diet-induced obesity. In line with the increases in transthyretin, properdin, and adipsin, ASP levels in serum were increased by 31-54% in IL-6(-/-) compared with IL-6(+/+) mice. Furthermore, IL-6 replacement treatment in IL-6(-/-) mice decreased ASP levels significantly by 25-60%. In conclusion, ASP levels are increased in preobese IL-6(-/-) mice. This increase may result in increased triacylglycerol formation and uptake in IL-6(-/-) adipocytes and thereby contribute to the development of obesity in IL-6(-/-) mice.