Assessment of Insulin Sensitivity in Older Adults Using the Hyperglycemic Clamp Technique

OBJECTIVE: The euglycemic glucose clamp technique is the gold standard for the measurement of insulin sensitivity in older adults, whereas the hyperglycemic glucose clamp technique is used to assess insulin release. The objective of this study was to evaluate the ability of the hyperglycemic glucose clamp technique to assess insulin sensitivity and insulin release in older people. RESEARCH DESIGN AND METHODS: Healthy older controls (n = 26, age 72 +/- 1) and older non-insulin-dependent diabetes mellitus (NIDDM) patients (n = 35, age 75 +/- 1) underwent a 2-hour hyperglycemic glucose clamp study (glucose 5.4 mM above basal) and a 3-hour euglycemic clamp study (insulin infusion rate 40 mU/m2/min). The average glucose infusion rate (last 30 minutes) of each clamp was divided by the average insulin value (last 30 minutes). This value was then divided by the average plasma glucose value to give glucose clearance per plasma insulin concentration. RESULTS: In control subjects (Eug: 0.80 +/- .05 mL/kg/min/pM; Hyper: 0.88 +/- .07 mL/kg/min/pM, P = .357) and NIDDM patients (Eug: 0.48 +/- .03 mL/kg/min/pM; Hyper: 0.42 +/- .03 mL/kg/min/pM, P = .162), glucose clearance values were similar whether calculated from the euglycemic or the hyperglycemic clamp. The correlation between glucose clearance values derived from the euglycemic and hyperglycemic clamp was excellent in normal controls (r = .76, P < .001) and patients with NIDDM (r = .71, P < .001). CONCLUSIONS: We conclude that the hyperglycemic glucose clamp technique can reliably assess both insulin release and insulin sensitivity in older people.