Insulin-stimulated increase in serum leptin levels precedes and correlates with weight gain during insulin therapy in type 2 diabetes

Astragalus mongholicus powder, a traditional Chinese medicine formula ameliorate type 2 diabetes by regulating adipoinsular axis in diabetic mice

The global morbidity of obesity and type 2 diabetes mellitus (T2DM) has dramatically increased. Insulin resistance is the most important pathogenesis and therapeutic target of T2DM. The traditional Chinese medicine formula Astragalus mongholicus powder (APF), consists of Astragalus mongholicus Bunge [Fabaceae], Pueraria montana (Lour.) Merr. [Fabaceae], and Morus alba L. [Moraceae] has a long history to be used to treat diabetes in ancient China. This work aims to investigate the effects of APF on diabetic mice and its underlying mechanism. Diabetic mice were induced by High-fat-diet (HFD) and streptozotocin (STZ). The body weight of mice and their plasma levels of glucose, insulin, leptin and lipids were examined. Reverse transcription-polymerase chain reaction, histology, and Western blot analysis were performed to validate the effects of APF on diabetic mice and investigate the underlying mechanism. APF reduced hyperglycemia, hyperinsulinemia, and hyerleptinemia and attenuate the progression of obesity and non-alcoholic fatty liver disease (NAFLD). However, these effects disappeared in leptin deficient ob/ob diabetic mice and STZ-induced insulin deficient type 1 diabetic mice. Destruction of either these hormones would abolish the therapeutic effects of APF. In addition, APF inhibited the protein expression of PTP1B suppressing insulin–leptin sensitivity, the gluconeogenic gene PEPCK, and the adipogenic gene FAS. Therefore, insulin–leptin sensitivity was normalized, and the gluconeogenic and adipogenic genes were suppressed. In conclusion, APF attenuated obesity, NAFLD, and T2DM by regulating the balance of adipoinsular axis in STZ + HFD induced T2DM mice.

Should We Monitor Glucose and Biomarkers in Diabetics over Heart Surgery?

Hyperglycemia is associated with adverse outcomes after coronary artery bypass grafting (CABG). While there is a consensus that blood glucose control may benefit patients undergoing CABG, the role of biomarkers, optimal method, and duration of such monitoring are still unclear. The aim of this study is to define the efficacy of a continuous glucose monitoring system (CGMS) and link it to pro-inflammatory biomarkers while on insulin pump therapy in diabetic patients undergoing CABG. We prospectively assessed CGMS for 72 h in 105 patients including 52 diabetics undergoing isolated CABG. In diabetics, CGMS was connected to an insulin pump for precise glucose control. On top of conventional biomarkers (HbA1C, lipid profile), high sensitive C-reactive protein (hs-CRP), Regulated upon Activation Normal T cell Expressed and presumably Secreted (RANTES), and leptin levels were collected before surgery, 1 h, 12 h, 7 days, and at 1 year after CABG. Overall, CGMS revealed high glucose independently from underlying diabetes during first 48 h following CABG but was higher (p < 0.05) in diabetics. The insulin pump improved glycemic control over early follow-up (72 h) post-CABG. There were no hypoglycemic episodes in patients on insulin pump therapy and those receiving bolus insulin therapy. We revealed a lower rate of postpericardiotomy syndrome (PCTS) in patients on insulin pump therapy compared to patients prescribed bolus insulin therapy in the early postoperative period (p = 0.03). Hs-CRP and RANTES levels were lower in patients with T2DM on insulin pump therapy compared to patients prescribed bolus insulin therapy in the early postoperative period (p < 0.05). It is most likely due to the fact that insulin pump therapy decreases systemic inflammatory response. Further controlled trials should assess whether CGMS improves outcomes after cardiac surgery.

Insulin resistance-associated genetic variants in type 1 diabetes

AIMS

To examine candidate insulin resistance single nucleotide polymorphisms (SNPs) for associations with glycemic control, insulin resistance, BMI, and complications in an observational type 1 diabetes (T1D) cohort: the Pittsburgh Epidemiology of Diabetes Complications (EDC) study.

METHODS

In 422 European-ancestry participants, we assessed associations using additive models between 15 candidate SNPs and 25-year mortality, cardiovascular disease, microalbuminuria, overt nephropathy and proliferative retinopathy, and 25-year mean HbA1c, estimated glucose disposal rate (eGDR, inverse measure of insulin resistance), and BMI.

RESULTS

The A allele of rs12970134 was associated with higher mean HbA1c (β = +0.34 ± 0.09, p = 0.00009) and nominally associated with worse eGDR (p = 0.02). Further analyses suggest the HbA1c association may be modified by diabetes therapy regimen: rs12970134 AA genotype was associated with higher HbA1c under non-intensive therapy conditions (<3 insulin injections/day or monitoring blood glucose<3 times/day [p = 0.004]), but not under intensive therapy (≥3 injections/day or insulin pump and monitoring glucose≥3 times/day [p = 0.71]). There were no significant associations between any SNPs and BMI or complications.

CONCLUSIONS

rs12970134, near MC4R, is strongly associated with HbA1c in this cohort. Further exploration of this genomic region is warranted, as it may hold promise for discovering new therapeutic targets to improve glycemic control in T1D.

The Role of Leptin in Maintaining Plasma Glucose During Starvation

For 20 years it has been known that concentrations of leptin, a hormone produced by the white adipose tissue (WAT) largely in proportion to body fat, drops precipitously with starvation, particularly in lean humans and animals. The role of leptin to suppress the thyroid and reproductive axes during a prolonged fast has been well defined; however, the impact of leptin on metabolic regulation has been incompletely understood. However emerging evidence suggests that, in starvation, hypoleptinemia increases activity of the hypothalamic-pituitary-adrenal axis, promoting WAT lipolysis, increasing hepatic acetyl-CoA concentrations, and maintaining euglycemia. In addition, leptin may be largely responsible for mediating a shift from a reliance upon glucose metabolism (absorption and glycogenolysis) to fat metabolism (lipolysis increasing gluconeogenesis) which preserves substrates for the brain, heart, and other critical organs. In this way a leptin-mediated glucose-fatty acid cycle appears to maintain glycemia and permit survival in starvation.

Leptin signaling in skeletal muscle after bed rest in healthy humans

PURPOSE

This study aimed at determining the effects of bed rest on the skeletal muscle leptin signaling system.

METHODS

Deltoid and vastus lateralis muscle biopsies and blood samples were obtained from 12 healthy young men (mean ± SD, BMI 22.8 ± 2.7 kg/m(2)) before and after 7 days of bed rest. Leptin receptor isoforms (OB-Rs), suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) protein expression and signal transducer and activator of transcription 3 (STAT3) phosphorylation were analyzed by Western blot.

RESULTS

After bed rest basal insulin concentration was increased by 53% (P < 0.05), the homeostasis model assessment (HOMA) by 40% (P < 0.05), and serum leptin concentration by 35% (P < 0.05) with no changes in body fat mass. Although the soluble isoform of the leptin receptor (s-OBR) remained unchanged, the molar excess of leptin over sOB-R was increased by 1.4-fold after bed rest (P < 0.05). OB-Rs and SOCS3 protein expression, and STAT3 phosphorylation level remained unaffected in deltoid and vastus lateralis by bed rest, as PTP1B in the deltoid. PTP1B was increased by 90% with bed rest in the vastus lateralis (P < 0.05). There was a linear relationship between the increase in vastus lateralis PTP1B and the increase in both basal insulin concentrations (r = 0.66, P < 0.05) and HOMA (r = 0.68, P < 0.05) with bed rest.

CONCLUSIONS

One week of bed rest is associated with increased leptin levels without augmenting STAT3 phosphorylation indicating some degree of leptin resistance in skeletal muscle, which can be explained, at least in part, by an elevation of PTP1B protein content in the vastus lateralis muscle.

Plasma leptin levels increase to a greater extent following on-pump coronary artery surgery in type 2 diabetic patients than in nondiabetic patients

AIMS

We aimed to evaluate whether leptin and ghrelin responses to cardiopulmonary bypass (CPB) are dependent on type 2 diabetes and whether these responses are associated with interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP), cortisol and insulin.

METHODS

We examined stress-response patterns in plasma leptin, ghrelin, hsCRP, IL-6, cortisol and insulin levels before and up to 5 days after cardiopulmonary bypass in 20 patients with type 2 diabetes and 20 patients without diabetes.

RESULTS

Plasma leptin levels increased significantly in both groups (p<0.05) and rose significantly higher in diabetics when compared with nondiabetic patients (p=0.004). Plasma ghrelin levels increased significantly only in diabetics (p=0.033). Patients with and without diabetes showed significantly elevated serum concentrations of IL-6, hsCRP, cortisol and insulin (p<0.005 for IL-6, hsCRP; p<0.05 for cortisol, insulin) but the difference between the two groups was nonsignificant. Leptin was independently predicted by hsCRP (p<0.05, F=2.9), gender (women p<0.001, F=4.7), body mass index (BMI p<0.0001, F=6.1) whereas ghrelin levels were not associated with any variables in the total patient population. (critical F=2.26, p≤0.05).

CONCLUSIONS

Acute phase response in diabetics differs by higher leptin levels independent of BMI, gender and IL-6, hsCRP, insulin and cortisol levels.

Alcoholism and diabetes mellitus

Chronic use of alcohol is considered to be a potential risk factor for the incidence of type 2 diabetes mellitus (T2DM), which causes insulin resistance and pancreatic β-cell dysfunction that is a prerequisite for the development of diabetes. However, alcohol consumption in diabetes has been controversial and more detailed information on the diabetogenic impact of alcohol seems warranted. Diabetes, especially T2DM, causes dysregulation of various metabolic processes, which includes a defect in the insulin-mediated glucose function of adipocytes, and an impaired insulin action in the liver. In addition, neurobiological profiles of alcoholism are linked to the effects of a disruption of glucose homeostasis and of insulin resistance, which are affected by altered appetite that regulates the peptides and neurotrophic factors. Since conditions, which precede the onset of diabetes that are associated with alcoholism is one of the crucial public problems, researches in efforts to prevent and treat diabetes with alcohol dependence, receives special clinical interest. Therefore, the purpose of this mini-review is to provide the recent progress and current theories in the interplay between alcoholism and diabetes. Further, the purpose of this study also includes summarizing the pathophysiological mechanisms in the neurobiology of alcoholism.

Amylin and selective glucoregulatory peptide alterations during prolonged exercise

Amylin is a pancreatic β-cell peptide that facilitates the regulation of blood glucose concentration by inhibiting release of glucagon and modulating gastric emptying. Prolonged exercise may alter amylin and aid in the maintenance of blood glucose concentration; however, no studies have investigated the effects of prolonged exercise on amylin.

PURPOSE

This study aimed to determine the effects of 90 min of treadmill exercise on amylin and other glucoregulatory hormone responses in a postprandial state.

METHODS

Eight young healthy males completed a preliminary trial for VO2max and body composition determination and subsequent experimental and control trials in a counterbalanced manner. The experimental trial subjects arrived at the laboratory at 8:00 a.m., 1 h after consumption of a standard nutrient beverage (Ensure Plus®). At 9:50 a.m., subjects initiated 90 min of treadmill exercise at 60% of VO2max. Blood samples were collected twice before exercise, every 18 min during exercise, and every 20 min during 1 h of recovery. A resting control trial was conducted in an identical manner without VO2 assessment.

RESULTS

Plasma glucose and leptin concentrations remained stable across exercise, whereas lactate significantly increased to peak at 18 min of exercise then gradually declined. Amylin, insulin, and C-peptide values significantly declined over the trials, with no difference between exercise and control days. Glucagon area-under-the-curve concentrations were significantly greater during the exercise than the control trials. There was a significant time effect and trial effect for cortisol with a higher concentration during the experimental trial than during the control trial.

CONCLUSIONS

In a postprandial state, prolonged exercise stimulates glucagon and cortisol increases that are associated with stable blood glucose and leptin concentrations; however, similar to postprandial state control condition, insulin, C-peptide, and amylin concentrations decline.

Effects of improving glycemic control with insulin on leptin, adiponectin, ghrelin and neuropeptidey levels in patients with type 2 diabetes mellitus: a pilot study

OBJECTIVE

Insulin therapy is associated with weight gain in patients with type 2 diabetes mellitus (T2DM). Several peptides are implicated in appetite control. We evaluated the effects of insulin-induced improved glycaemic control on leptin, adiponectin, ghrelin, neuropeptide Y (NPY) levels and patient characteristics.

METHOD

Consecutive T2DM patients (n = 90) were divided into 2 groups: Group A: 45 insulin-naïve uncontrolled (glycosylated haemoglobin A(1c); HbA(1c )>7%) patients on oral hypoglycaemic agents (OHAs) who converted to insulin monotherapy. Group B: 45 well-controlled (HbA(1c )<7%) patients on OHAs. Both groups were monitored at baseline, 3 and 6 months. Males and females were analyzed separately because some hormone levels differ between genders.

RESULTS

In both genders, insulin therapy (Group A) was associated with significant (p = 0.003 to <0.001) increases in weight, body mass index and leptin levels and significant decreases in glucose, HbA(1c) and NPY levels. In male insulin-treated patients a significant increase in adiponectin levels (p = 0.008) was observed. There were significant correlations (p = 0.016 to <0.001) between leptin levels, waist circumference and body fat in all patient groups, except group B males.

CONCLUSION

Changes in leptin, adiponectin and NPY levels may occur after insulin-induced improved glycaemic control. These changes may be influenced by gender, weight, body fat and HbA(1c).