GROWTH-HORMONE (GH) REPLACEMENT REDUCES TOTAL-BODY FAT AND NORMALIZESINSULIN SENSITIVITY IN GH-DEFICIENT ADULTS - A REPORT OF ONE-YEAR CLINICAL-EXPERIENCE

The effects of GH replacement on body fat composition and insulin sens itivity were assessed in GH-deficient adults. The patients were random ized into a double-blind, placebo-controlled study of human recombinan t GH replacement therapy for 6 months (period 1), followed by an open phase of GH for another 6 months (period 2). Anthropometric variables, body fat composition (fat %), and biochemical parameters were measure d during the trial. Measurements of in vivo insulin sensitivity were c arried out at the commencement of the study and on completion of the t rial by modified insulin suppression test. The modified insulin suppre ssion test was performed both in the morning (AM) and in the afternoon (PM) to further evaluate the PM-AM steady-state plasma glucose (SSPG) pattern. We found that the GH-deficient adults had more body fat and were insulin resistant. Significant reduction in fat % and total body fat mass was found in the active arm of period 1 without alteration of body weight. Besides, we demonstrated, for the first time, that GH re placement for 6 months did not alter the insulin Sensitivity, but repl acement for a longer period (12 months) normalized not only the AM SSP G level but also the PM-AM SSPG pattern. We also found a positive corr elation between SSPG (regardless of AM vs. PM) and fat % and total bod y fat mass. In conclusion, normalization of insulin sensitivity in GH- deficient adults after replacement of GH may be related to the reducti on of total body fat.