Relationships between glucose metabolism and thermogenesis with and without prior exercise in obese women with non-insulin-dependent diabetes mellitus

The rate of insulin-stimulated glucose disposal is reduced in individuals with insulin resistance, and is associated with a blunted or absent increase in energy expenditure in response to a glucose load. The magnitude of the effect of glucose on energy expenditure (EGEE) may be a function of opposing changes in the rate of glucose disposal (Rd) and hepatic glucose production (HGP). In this study, six women with non-insulin-dependent diabetes mellitus (NIDDM) were studied on a metabolic ward in each of three conditions. On days 1 and 2, they did no exercise (NX) or else performed low-intensity exercise ([LO] 3,118 kJ [745 kcal]) at 50% maximal oxygen consumption [Vo(2)max]) or high-intensity exercise ([HI] 3,114 kJ [744 kcal] at 75% Vo(2)max). On day 3, infusion of 6,6(2)4H-glucose in the basal state was immediately followed by infusion of glucose, 6,6(2)H-glucose, and insulin at fixed rates. Indirect calorimetry was performed during the last 30 minutes of each infusion. EGEE was not different among the three conditions (mean +/- SEM: NX -0.18 +/- 0.11, LO -0.08 +/- 0.05, and HI -0.08 +/- 0.07 kJ/min) and was inversely related to steady-state plasma glucose concentration, a direct measure of insulin resistance (r =-.89, P <.05). EGEE was positively correlated with glucose Rd (r =.94, P <.001) and negatively correlated with HGP (r =-.91, P <.05). The data indicate that the glucose effect on energy expenditure was slightly positive in the more insulin-sensitive individuals, but negative in the more insulin-resistant subjects. The EGEE appears to be determined by the relative balance between energy required to store glucose and energy saved by suppression of glucose production. Copyright (C) 1996 by W.B. Saunders Company.