We examined oral glucose tolerance, plasma lipid/lipoprotein levels, and whole body leucine kinetics in very old physically frail men and women, and compared them to the same parameters measured previously in 60-70yr old healthy men and women to assess whether advancing age and reduced physical activity alter substrate metabolism. In comparison to the 60-70yr old men (n=143,66±7yr,70±13kg) and women (n=261,66±6yr,81±11kg), there was a trend towards higher plasma glucose and insulin levels in frail men (n=12,82±5yr,66±15kg) and women (n=44,80±3yr,68+14kg) 1-2h after a 75g oral glucose challenge. Whether this is a result of reduced physical activity or co-morbid conditions remains to be determined. Plasma total CHOL,TRIGL and HDL levels were not different between the 60-70yr old men (n=121) and women (n=235) and the older frail men and women, suggesting that the tendency towards insulin resistance in the frail adults does riot adversely affect lipid/lipoprotein profiles. Whole body protein kinetics were assessed using a constant intravenous 13C-leucine infusion in 4 frail women (85±4yr,54±4kg) and compared to four 60-67yr old women (64±3yr,70±11kg). Lower rates (P<0.05) of fasting whole body protein breakdown (108vs150μmol/kg FFM/h), protein synthesis (84vs116μmol/kg FFM/h) and leucine oxidation (24vs33μmol/kg FFM/h) were observed in the frail women than in the 60-67yr old women, suggesting that whole body protein turnover is reduced in physically frail women, perhaps to conserve nitrogen and protect against pro-tein wasting.
|State||Published - Dec 1 1997|