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7th International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV13–16 November 2005, Dublin, Ireland |
Use of oral glucose tolerance testing to estimate insulin sensitivity in patients with HIV infection
K Mulligan, JC Lo, H Khatami and M Schambelan
University of California, San Francisco, CA, USA
Antiviral Therapy 2005; Supplement 3:L10 (abstract no. 13)
OBJECTIVES: The glucose clamp is considered the criterion technique for measurement of insulin sensitivity, but is not suitable for large population-based studies. In contrast, the oral glucose tolerance test (OGTT) is a relatively simple procedure that can be performed in large numbers of subjects in a clinic setting. In this analysis, we compare insulin sensitivity measured by glucose clamp with that derived from an OGTT in HIV-positive subjects.
METHODS: Thirty-two HIV-positive men with a wide range of body fat content (7–38% by DEXA) were hospitalized in a metabolic ward for 5 days and consumed a constant eucaloric diet. On day 3, they underwent a 75g OGTT, with blood samples collected at t=0, 30, 60, 90, 120 and 180 min. On day 5 they underwent a 3-h euglycaemic hyperinsulinaemic clamp. Serum insulin concentrations during the OGTT and clamp were measured in the same assay for each subject. Surrogate estimates of insulin sensitivity (insulin sensitivity index [ISI] derived from the OGTT by Matsuda and DeFronzo; and HOMA-IR and QUICKI using fasting [t=0] measurements for the clamp) were compared with insulin-mediated glucose uptake (M/I) measured during the third hour of the clamp.
RESULTS: The ISI calculated from the 3-h OGTT was highly correlated with M/I (r=0.870, P=1.02×10-10). Notably, the correlation coefficient for ISI calculated using data from only the first 2 h of the OGTT was almost as high (r=0.854; P=5.1×10-10). The correlations of HOMA-IR and QUICKI with M/I were similar and highly significant but not as robust as the ISI (r=–0.712, P=7.1×10–6; r=0.737, P=2.2×10-6 for HOMA-IR and QUICKI, respectively). Log transformation improved these latter correlations only slightly.
CONCLUSION: Although the OGTT is not primarily intended to measure insulin sensitivity, our results suggest that measurements of glucose and insulin during a 2- or 3-h OGTT can be used to provide an estimation of insulin sensitivity in patients with HIV infection that is highly correlated to results obtained by the glucose clamp technique and is superior to estimates of insulin sensitivity or resistance based on fasting measurements alone.
ACKNOWLEDGMENTS: NIH (DK45833, DK54615, DK63640, DK69185; RR-00083).
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2005-11-13
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