RELATIONSHIP OF GENERALIZED AND REGIONAL ADIPOSITY TO INSULIN SENSITIVITY IN MEN WITH NIDDM

Abdominal obesity, particularly excess intraperitoneal fat, is conside red to play a major role in causing insulin resistance and NIDDM. To d etermine if NIDDM patients accumulate excess intraperitoneal fat, and whether this contributes significantly to their insulin resistance, 31 men with mild NIDDM with a wide range of adiposity were compared with 39 nondiabetic, control subjects for insulin sensitivity (measured us ing euglycemic-hyperinsulinemic clamp technique with [3-H-3]glucose tu rnover) and total and regional adiposity (assessed by hydrodensitometr y and by measuring subcutaneous abdominal, intraperitoneal, and retrop eritoneal fat masses using magnetic resonance imaging [MRI], and trunc al and peripheral skinfold thicknesses using calipers). MRI analysis r evealed that intraperitoneal fat was not increased in NIDDM patients c ompared with control subjects; in both groups it averaged 11% of total body fat, NIDDM patients, however, had increased truncal-to-periphera l skinfolds thickness ratios. In NIDDM patients, as in control subject s, amounts of truncal subcutaneous fat showed a stronger correlation w ith glucose disposal rate than intraperitoneal or retroperitoneal fat; however, NIDDM patients were more insulin resistant at every level of total or regional adiposity. Further, no particular influence of exce ss intraperitoneal fat on hepatic insulin sensitivity was noted. We co nclude that NIDDM patients do not have excess intraperitoneal fat, but that their fat distribution favors more truncal and less peripheral s ubcutaneous fat. Moreover, for each level of total and regional adipos ity, NIDDM patients have a heightened state of insulin resistance.