Insulin-resistant patients with type 2 diabetes mellitus have higher serum leptin levels independently of body fat mass

Obesity, adipocytokines, and insulin resistance in breast cancer

The adipocytokines are biologically active polypeptides that are produced either exclusively or substantially by the adipocytes, and act by endocrine, paracrine, and autocrine mechanisms. Most have been associated with obesity, hyperinsulinaemia, type 2 diabetes, and chronic vascular disease; in addition, six adipocytokines--vascular endothelial growth factor, hepatocyte growth factor, leptin, tumour necrosis factor-alpha, heparin-binding epidermal growth factor-like growth factor, and interleukin-6--promote angiogenesis while one, adiponectin, is inhibitory. Obesity and insulin resistance have both been identified as risk factors for breast cancer and are associated with late-stage disease and poor prognosis. Angiogenesis is essential for breast cancer development and progression, and so it is plausible that obesity-related increases in adipocytokine production and a reduction in adiponectin may adversely affect breast cancer outcome by their angiogenesis-related activities. There is also experimental evidence that some adipocytokines can act directly on breast cancer cells to stimulate their proliferation and invasive capacity. Thus, adipocytokines may provide a biological mechanism by which obesity and insulin resistance are causally associated with breast cancer risk and poor prognosis. Both experimental and clinical studies are needed to develop this concept, and particularly in oestrogen-independent breast cancers where preventive and therapeutic options are limited.

Fenofibrate treatment is associated with better glycemic control and lower serum leptin and insulin levels in type 2 diabetic patients with hypertriglyceridemia

Background: Hertriglyceridemia is commonly encountered in type 2 diabetic patients. Fibrates are a group of drugs that efficiently decrease triglycerides, increase HDL, and improve the prognosis in both diabetic and nondiabetic patients. However, the effects of fibrates on glycemic control, blood pressure, fasting serum insulin, and leptin concentrations are not clear. The present study addresses the question of whether fenofibrate treatment in hypertriglyceridemic type 2 diabetic patients leads to changes in metabolic control, body mass index, leptin, free fatty acids, plasma insulin, and blood pressure. Methods: Thirty-one type 2 diabetic patients who had serum triglyceride levels between 250 and 400 mg/dl were included in the study. They were given 250 mg/day fenofibrate once daily for 3 months. Antidiabetic and antihypertensive treatments were kept unchanged throughout the study. Results: Fenofibrate treatment resulted in better glycemic control, as evidenced by lower fasting and postprandial blood glucose and HbAlc, decreased fasting serum insulin and leptin levels, as well as a reduction in hypertrigyceridemia and serum free fatty acids, and an increase in HDL cholesterol. Blood pressure, body mass index, and LDL remained unchanged. Fenofibrate was well tolerated in all patients. Conclusion: Fenofibrate treatment in hypertriglyceridemic type 2 diabetic patients is beneficial not only in terms of lipid profile, but also for glycemic control and insulin resistance.

Effect of lifestyle modification on adipokine levels in obese subjects with insulin resistance

OBJECTIVE

To study the effect of weight loss in response to a lifestyle modification program on the circulating levels of adipose tissue derived cytokines (adipokines) in obese individuals with insulin resistance.

RESEARCH METHODS AND PROCEDURES

Twenty-four insulin-resistant obese subjects with varying degrees of glucose tolerance completed a 6-month program consisting of combined hypocaloric diet and moderate physical activity. Adipokines [leptin, adiponectin, resistin, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6)] and highly sensitive C-reactive protein were measured before and after the intervention. Insulin sensitivity index was evaluated by the frequently sampled intravenous glucose tolerance test.

RESULTS

Participants had a 6.9 +/- 0.1 kg average weight loss, with a significant improvement in sensitivity index and reduction in plasma leptin (27.8 +/- 3 vs. 23.6 +/- 3 ng/mL, p = 0.01) and IL-6 (2.75 +/- 1.51 vs. 2.3 +/- 0.91 pg/mL, p = 0.012). TNF-alpha levels tended to decrease (2.3 +/- 0.2 vs. 1.9 +/- 0.1 pg/mL, p = 0.059). Adiponectin increased significantly only among diabetic subjects. The reductions in leptin were correlated with the decreases in BMI (r = 0.464, p < 0.05) and with changes in highly sensitive C-reactive protein (r = 0.466, p < 0.05).

DISCUSSION

Weight reduction in obese individuals with insulin resistance was associated with a significant decrease in leptin and IL-6 and a tendency toward a decrease in circulating TNF-alpha, whereas adiponectin was increased only in diabetic subjects. Further studies are needed to elucidate the relationship between changes of adipokines and the health benefits of weight loss.