THERMAL AND METABOLIC RESPONSES TO ORAL GLUCOSE IN OBESE SUBJECTS WITH NON-INSULIN-DEPENDENT DIABETES-MELLITUS TREATED WITH INSULIN OR A VERY-LOW-ENERGY DIET

Increased resting energy expenditure (REE) and a blunted thermic effec t of glucose (TEF) have been reported in obese subjects with non-insul in-dependent diabetes mellitus (NIDDM). I questioned whether the abnor mal REE and TEF would be corrected by normalizing glycemia with insuli n or a very-low-energy diet (VLED). Three male and four female obese s ubjects with NIDDM [weighing 108 +/- 6 kg and with body mass index (in kg/m(2)) of 39 +/- 2] received a weight-maintaining formula diet cont aining 95 g protein/d for 15 d then a 1.7-MJ, 93-g-protein VLED for 27 d. Insulin was given from days 1 to 8 in doses sufficient to normaliz e glycemia. REE was measured weekly and TEF was measured on days 8 and 15 of isoenergetic feeding and 28 d after the VLED by using a ventila ted-hood indirect calorimeter. Weight decreased 9.8 +/- 1 kg during th e VLED. REE was 3% lower with insulin treatment than during hyperglyce mia (7878 +/- 364 compared with 8125 +/- 381 kJ/d, P = 0.002). REE dec reased by 20% to 6494 +/- 280 kJ/d by week 4 of the VLED. After 112 g oral glucose, increments in energy expenditure were significantly grea ter during isoenergetic feeding with insulin than without (7.5 +/- 1.3 % compared with 4.3 +/- 0.9% above REE) and after the VLED (10.5 +/- 1 .0% above REE, P < 0.05). Plasma glucose excursions were greatest with out exogenous insulin (peak 21.5 +/- 1.8 mmol/L at 120 min, 16.3 +/- 1 .9 mmol/L at 225 min). Plasma fatty acid excursions were the lowest wi th insulin treatment. The integrated plasma glucose and fatty acid res ponses above baseline did not differ among studies; the integrated ins ulin and C-peptide responses were greater after the VLED. Cumulative n onoxidative glucose disposal (stored glucose) was higher with insulin therapy than without (52 +/- 6 compared with 35 +/- 7 g/210 min, P < 0 .05) and increased significantly to 66 +/- 6 g after the VLED (compare d with the isoenergetic diet without insulin). TEF correlated signific antly with integrated C-peptide and insulin responses. The percentage increase in TEF with euglycemia with insulin and VLED) correlated with the percentage increase in stored glucose (P < 0.05). The greater TEF was associated with a greater insulin response, which was probably re sponsible for the greater stored glucose.