DIETARY RESTRICTION INCREASES INSULIN SENSITIVITY AND LOWERS BLOOD-GLUCOSE IN RHESUS-MONKEYS

Insulin sensitivity and glucose tolerance typically decline during lat er life. In a multidimensional randomized trial of the effects of diet ary restriction started in adulthood on the processes of aging, we are studying insulin sensitivity and glucoregulation longitudinally in co ntrol (C, n = 15, fed a defined diet ad libitum for 6-8 h/day) and res tricted (R, n = 15, fed 30% less than C) monkeys using the Modified Mi nimal Model method. Linear rates of change were calculated for individ ual animals through 30 mo of diet treatment and compared between treat ment groups. Basal glucose, basal insulin, and insulin responses to gl ucose and tolbutamide increased for C and decreased for R animals (P l ess than or equal to 0.002), whereas insulin sensitivity decreased for C and increased for R (P = 0.008). Glycosylated hemoglobin at 30 mo w as marginally lower in R (P = 0.06) and was positively correlated with fasting plasma glucose (r = 0.508, P < 0.001). Insulin changes were s ignificantly correlated with changes in adiposity (weight and abdomina l circumference). Identification of the mechanisms through which these effects are achieved may aid in ameliorating glucose intolerance, ins ulin resistance, and associated illnesses in older persons.