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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, METHODS, METHODS, RESULTS. Meshes: Adipose Tissue, Age Factors, Aged, Aging, Blood Glucose, Body Constitution, Body Mass Index, Cholesterol, HDL, Cholesterol, LDL, Fasting, Fatty Acids, Nonesterified, Female, Follow-Up Studies, Forecasting, Glucose, Glucose Clamp Technique, Humans, Insulin, Insulin-Like Growth Factor Binding Protein 3, Insulin-Like Growth Factor I, Longitudinal Studies, Male, Motor Activity, Oxidation-Reduction, Respiration, Sex Factors, Triglycerides.
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Do low plasma insulin-like growth factor-1 concentrations predict worsening of insulin-mediated glucose uptake in older people? Context: The relationship among insulin action, advancing age, and insulin like growth factor-1 (IGF-1) is poorly understood. To gain further insight, the predictive role that low plasma IGF-1 concentration may have on insulin- mediated glucose uptake in older persons was investigated. The study was designed as a longitudinal, observational trial. Fifty-eight healthy aged (73.1+/-9.4 years) subjects (31 males/27 females) were followed up for 12 months. At baseline and at the end of the follow-up, insulin-mediated glucose uptake was assessed by euglycemic glucose clamp and plasma total IGF-1 and IGF-binding protein 3 (IGF-BP-3) in each subject, and concentrations were determined. At baseline, plasma IGF-1 concentrations correlated with whole body glucose uptake (WBGD) (r = 0.39, P < .003), insulin-stimulated glucose oxidation (GOX) (r = 0.35, P < .009), and non-oxidative glucose metabolism (r = 0.37, P < .007). Such correlations were also independent of age, sex, body fat, and waist/hip ratio. Fasting plasma total IGF-1 concentrations (84+/-56 vs 63+/-44 microg/L, P < .040), plasma IGF-1/IGF-BP3 molar ratio (0.13+/-0.05 vs 0.10+/-0.03 P < .050), and WBGD (34.8+/-5.0 vs 23.1+/-4.6 micromol/kg x min, P < .010) were more elevated at baseline than at the end of the follow-up. Low baseline fasting plasma IGF-1 concentration (RR = 1.5, 95%CI = 1.3-1.7) and plasma IGF-1/IGFBP-3 molar ratio (RR = 1.4, 95% CI = 1.3-1.8) predicted a decline in WBGD. The predictive role of plasma IGF-1 on age-related decline in WBGD was independent of age, sex, body fat, waist/hip ratio, and degree of physical activity (model 1), or of fasting plasma free fatty acid and triglyceride concentrations, LDL/HDL ratio, and basal adjusted respiratory quotient (model 2). Finally, low plasma IGF-1 concentration predicts a decline in WBGD independent of body fat, free fatty acids, waist/hip ratio, and basal adjusted respiratory quotient (model 3).
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Our study demonstrates that fasting plasma IGF-1 concentration may have a modulatory role on insulin action in older people. This finding might prompt an evaluation of the direct effect of IGF-1 administration on insulin sensitivity in older adults. Final Decision: yes