Lack of postprandial leptin peaks in patients with type 2 diabetes mellitus.

Overview

Leptin production by the adipocyte is acutely stimulated by insulin in vitro. In normal individuals, postprandial insulin peaks are not accompanied by corresponding changes in circulating leptin. Postprandial regulation of leptin in individuals with type 2 diabetes, to our knowledge, has not been previously examined in detail. We examined the effect of meals on circulating leptin levels in six patients with type 2 diabetes who were not treated with insulin and in seven normal individuals. After informed consent was obtained, all subjects were admitted to the General Clinical Research Center for 6 days. They consumed four meals daily (breakfast, lunch, dinner and snack). Eighteen blood samples were drawn between 7.40 a.m. and midnight for the determination of serum leptin, insulin and glucose levels. Postprandial peaks were clearly identifiable for glucose and insulin levels both in normal subjects and in those with type 2 diabetes. However, no postprandial peaks of leptin levels were present. Correlation analysis demonstrated a lack of correlation between leptin levels and the levels of glucose or insulin. We conclude that, in spite of the presence of postprandial insulin peaks, there are no acute changes in circulating leptin levels postprandially in patients with type 2 diabetes who are not on insulin therapy. In this regard, in-vivo regulation of leptin by meals in patients with type 2 diabetes is similar to that in normal individuals.