Leptin concentration in non-obese and obese children with type 1 diabetes mellitus

Leptin, the product of the ob gene, is an adipocyte-derived hormone that positively correlates with body fat percantage and body mass index (BMI). There are many data which demonstrate a significant relationship between leptin and insulin, but the mechanism underlying the changes of leptin induced by insulin and vice versa remains to be studied in more detail. In this review, we analysed the data on the behaviour of serum leptin levels in non-obese and obese children with type 1 diabetes mellitus. It has been shown that the diminished serum leptin concentrations in patients with newly discovered insulin-dependent diabetes mellitus (IDDM) could be caused by insulin deficiency and/or increased lipolysis. Moreover, while in some studies in diabetic children with good metabolic control the serum leptin levels are similar to those of healthy children, in other studies children with IDDM have leptin levels higher than non diabetic children; it is possible that in some diabetic children intensified insulin therapy could cause chronic hyperinsulinemia with high leptin levels. The mean serum leptin concentrations in the obese diabetic subjects were significantly higher when compared with non-obese diabetics. Obese diabetic patients showed no significant differences in leptin concentrations in comparison to the non diabetic obese group matched by age, sex and BMI. In obese diabetics, during weight loss, independent of the quality of metabolic control, serum leptin concentration declines. The changes of leptin in diabetes seem to be similar to those observed in healthy obese subjects.