Increased rate of Cori cycle in obese subjects with NIDDM and effect of weight reduction.

To determine the contribution of the rate of glucose recycling via the Cori cycle (glucose----3-carbon compounds----glucose) to the higher rate of endogenous glucose production (EGPR) in subjects with non-insulin-dependent diabetes mellitus (NIDDM), we studied eight obese, weight-stabilized diabetic Pima Indians before [93.1 +/- 5.4 kg, 38 +/- 2% body fat, fasting plasma glucose (FPG) 254 +/- 11 mg/dl] and after (87.7 +/- 4.7 kg, 36 +/- 2% body fat, FPG 153 +/- 17 mg/dl) a 5-wk weight-loss diet and eight obese Indians (95.0 +/- 4.2 kg, 36 +/- 2% body fat, FPG 97 +/- 1 mg/dl) with normal glucose tolerance. EGPR and glucose recycling rate were measured during a 4-h primed continuous tracer infusion of [1-13C]glucose, and the rate of reincorporation of 1-13C of glucose into C2-6 positions in glucose was quantified by gas chromatography mass spectrometry. Substrate utilization rates were measured by simultaneous indirect calorimetry. EGPR (corrected for measured rate of recycling) decreased in the diabetic subjects from 3.80 to 2.74 mg.min-1.kg-1 fat-free mass (FFM) (P less than .01) after weight loss, approaching the rate observed in nondiabetic subjects (2.09 mg.min-1.kg-1 FFM).(ABSTRACT TRUNCATED AT 250 WORDS)