GLUCOSE AND FAT-METABOLISM IN ADULTS WITH GROWTH-HORMONE DEFICIENCY

OBJECTIVE Adults with long-standing GH deficiency have a decreased lea n body mass and an increased fat mass. We investigated the effects of the abnormal body composition on glucose turnover and fuel metabolism. DESIGN Cross-sectional analysis PATIENTS Twenty-four adults with acqu ireed GH deficiency and a wide range of adiposity (body mass index fro m 18.8 to 42.3 kg/m(2)). MEASUREMENTS In the post-absorptive state glu cose turnover was measured following intravenous injection of 3-H-3-gl ucose and leucine oxidation was assessed following intravenous injecti on of 1-C-14-leucine. Glucose and fat oxidation were calculated from i ndirect calorimetry using protein oxidation derived from leucine oxida tion. RESULTS Total glucose turnover was 692 +/- 146 mu mol/min (mean +/- SD) and increased with height (r = 0.70, P = 0.0003) and with lean body mass (LBM) (r = 0.80, P < 0.0001). Glucose turnover expressed pe r kg LBM was in the published normal range (14.2 +/- 2.1 mu mol/kg LBM min). Glucose oxidation was 47 +/- 27% of glucose turnover and increa sed with LBM (r = 0.61, P = 0.006). The non-oxidative part of glucose turnover was positively correlated with fat oxidation (r = 0.82, P = 0 .0001) and inversely with the respiratory quotient (r = -0.81, P < 0.0 001). Ketone body concentration (r = 0.55, P = 0.33), but not free fat ty acid levels (r = 0.21, NS), correlated with fat oxidation. Fasting plasma glucagon levers were elevated (35 +/- 13 vs 9 +/- 19 pmol/l (pu blished controls)) and inversely related to lean body mass (r = -0.44, P = 0.04). CONCLUSIONS Adults with GH deficiency studied after an ove rnight fast have changes in glucose and fuel metabolism seen in normal subjects after more prolonged fasting suggesting that adults with hor mone deficiency have reduced carbohydrate stores.