Postprandial insulin sensitivity and thermogenesis in frail elderly women

The frailty syndrome is associated with inflammation, hypercortisolemia, and cardiovascular diseases, all of which are linked with insulin resistance. But whether frailty is characterized by insulin resistance is unclear, especially in the postprandial state. The prevalence of underweight with frailty is high. We wondered whether hypermetabolism associated with inflammation and hypercortisolemia could increase the thermic effect of food (TEF) and contribute to the frailty-associated body weight loss. In this study, we determined whether insulin sensitivity and TEF responses differ between frail and healthy elderly persons following a meal. Ten healthy and 13 frail elderly women were recruited and studied during the 5 h following the ingestion of a standardized liquid mixed-meal test. Areas under the curve (AUC) for glucose and insulin, and the product of AUC glucosexAUC insulinx10(−6) (PGI) were used as indices of insulin sensitivity. TEF was measured by indirect calorimetry. Following the meal, glucose and insulin AUCs and PGI were significantly higher in frail than in healthy elderly women and, except for the insulin AUC; these differences remained significant after adjustment for age, body weight, and physical activity. Physical activity, determined by questionnaire, was the single best predictor of PGI, explaining 27% of its variance. There was no difference in TEF between groups, and it did not correlate with any significant variable measured. Our results suggest that postprandial insulin resistance is higher in frail than in healthy elderly women, and TEF is similar, indicating that both processes do not contribute to the propensity for body weight loss.