Objective: To investigate whether there are differences in serum leptin levels between the offspring of non-insulin-dependent diabetes mellitus (NIDDM) patients representing different phenotypes of NIDDM, and furthermore to investigate the role of different fat tissue (subcutaneous fat area (SCFAT) and intra-abdominal fat area (IAFAT)) and insulin sensitivity on serum leptin levels.
Design: Twenty non-diabetic offspring of NIDDM patients with insulin secretion deficient phenotype (IS-group), 18 non-diabetic offspring of NIDDM patients with insulin resistant phenotype (IR-group) and 14 healthy control subjects without a family history of diabetes were studied.
Methods: Serum leptin levels were measured by RIA. SCFAT and IAFAT were measured by computed tomography. the total fat mass (TFM) by bioelectrical impedance and the whole body glucose uptake (WBGU) by the euglycemic hyperinsulinemic clamp technique.
Results: Subjects of the control group (P = 0.003) and the IS-group (P<0.001) had lower serum leptin levels than subjects of the IR-group even after adjustment for gender (P<0.001). TFM (P = 0.009), fasting plasma insulin (P = 0.003) and for IAFAT (P<0.001). The differences weakened after adjustments for SCFAT (P = 0.028) or WBGU (P = 0.040) and disappeared after adjustment for both SCFAT and WBGU (P = 0.058). In the stepwise multiple regression analyses SCFAT. WBGU and gender explained 58% of the variation of serum leptin levels whereas IAFAT failed to be a significant determinant of serum leptin levels.
Conclusions: The higher serum leptin levels in the IR-group was markedly, but not solely, explained by lower rates of WBGU and higher SCFAT. SCFAT was shown to be a more important determinant of serum leptin levels than IAFAT among these study groups.