Insulin resistance syndrome in the elderly: assessment of functional, biochemical, metabolic, and inflammatory status.

OBJECTIVE: Hyperinsulinemic euglycemia, or insulin resistance syndrome (IRS), is associated with increased morbidity and mortality. Although thought to be associated with proinflammatory states, little work has been done in this area. Here, we determined the impact of IRS on functional, biochemical, metabolic, and inflammatory status in a high-risk population: elderly women in nursing homes. RESEARCH DESIGN AND METHODS: Functional, biochemical, metabolic, and inflammatory parameters were measured in 100 consecutive ambulatory, elderly women who resided in nursing homes. Diabetic subjects and residents with fasting blood glucose >or=110 mg/dl were excluded. Remaining residents were classified as insulin resistant (IR) (insulin >100 pmol/l) or non-IR (NIR).
RESULTS: A total of 16 residents were IR and 53 NIR. No differences in functional status, BMI, renal function, C-reactive protein, or immune cell levels were found. Fasting blood glucose was higher in IR subjects ([means +/- SD] 94.1 +/- 8.1 vs. 87.9 +/- 8.2, P < 0.05), indicating a very mild glucose intolerance. Serum C-peptide (P < 0.05), amylin (P < 0.01), and leptin (P < 0.01), but not adiponectin or resistin, were higher in IR subjects. Higher leptin-to-BMI and insulin-to-C-peptide ratios suggested an increased percent body fat mass and altered clearance of insulin, respectively. Eleven of 13 cytokines had arithmetic elevations, but only tumor necrosis factor-alpha (TNF) reached statistical significance (P < 0.01). TNF and insulin levels were highly correlated.
CONCLUSIONS: IRS in the healthiest of long-term care residents is relatively rare but is associated with mild glucose intolerance, increased percent body fat, altered insulin clearance, and a proinflammatory status as evidenced by an elevated TNF.