SIMILAR INSULIN SENSITIVITY IN NIDDM PATIENTS WITH NORMOALBUMINURIA AND MICROALBUMINURIA

OBJECTIVE - To investigate whether insulin resistance and microalbumin uria are associated in non-insulin-dependent diabetes mellitus (NIDDM) . RESEARCH DESIGN AND METHODS- Insulin sensitivity was assessed using a hyperinsulinemic euglycemic clamp in 11 normoalbuminuric and 9 micro albuminuric NIDDM patients matched for sex, age, body composition, gly cemic control, diabetes duration, and therapy. RESULTS - Isotopically determined glucose disposal was similar in normo- and microalbuminuric patients in the basal state (mean +/- SD; 3.30 +/- 1.01 vs. 3.46 +/- 0.82 mg . kg lean body mass [LBM](-1) . min(-1); NS) and during hyperi nsulinemia (7.16 +/- 2.65 vs. 6.63 +/- 2.88 mg . kg LBM(-1) . min(-1); NS). No difference was observed in nonoxidative glucose disposal or l ipid oxidation. Endogenous glucose production was equally suppressed b y insulin (-0.08 +/- 0.99 vs. 0.30 +/- 1.12 mg . kg(-1) LBM . min(-1); NS). Glucose oxidation tended to be lower in the normoalbuminuric pat ients in the basal state (1.16 +/- 0.37 vs. 1.41 +/- 0.36 mg . kg LBM( -1) . min(-1)) and during hyperinsulinemia (2.35 +/- 0.72 vs. 2.90 +/- 0.77 mg . kg LBM(-1) . min(-1); both P < 0.15). Urinary albumin excre tion rate correlated with the insulin-stimulated glucose oxidation rat e (r = 0.59, P = 0.0064), and a similar trend was seen In the basal st are (r = 0.42, P = 0.063). Protein oxidation was higher in normoalbumi nuric patients (1.6 +/- 0.5 vs. 1.0 +/- 0.4 mg . kg LBM(-1) . min(-1); P = 0.017) and correlated inversely with albuminuria (r = -0.70, P = 0.0007). Serum growth hormone increased during insulin infusion; howev er, the increase was significantly greater in microalbuminuric patient s. Plasma lipoproteins, maximal aerobic capacity, and 24-h ambulatory blood pressure were similar in the two groups. CONCLUSIONS - Basal and insulin-stimulated glucose uptakes are comparable in carefully matche d normo- and microalbuminuric NIDDM patients, and glucose oxidation ma y be positively related to albuminuria. The inverse relation between p rotein oxidation and albuminuria may be due to higher growth hormone l evels during daily life perturbations in glucose in microalbuminuric p atients.