Session: SUN 780-806-Determinants of Insulin Resistance & Associated Metabolic Disturbances
Poster Board SUN-789
Objective: To determine which OGTT-derived indices give the best prediction of indices from IVGTT, i.e. SI and its reciprocal insulin resistance (1/SI), AIRg (acute-insulin-response-to-glucose measuring insulin secretion), and DI (disposition index =SIxAIRg measuring b-cell compensation).
Methods: AAM (N=50, A1C 5.7-6.9%, not on any anti-diabetic medications) were recruited from an inner city VA as part of an ongoing clinical trial and underwent OGTT and IVGTT. We calculated 29 OGTT-derived indices based on the formulas from the previous studies and our own and correlated these with IVGTT-derived indices. The accuracy of the empiric formulas obtained were evaluated with Bland-Altman plots.
Results: Subject characteristics and OGTT-derived values were (Mean±SD): age 60.0±4.8yrs; BMI 32.2±2.5kg/m2; glucose (G, mg/dl) fasting (Gf) 98.6 ±15.0, mean (Gm) 129±22, peak (Gp) 185±40; insulin (I) (µU/ml) fasting (If) 18.6±16.5, mean (Im) 13.9±6.2, peak (Ip) 223.3±92.8; mean area under the glucose curve (AUCGm=AUCGtotal/number of time points) 2707±533; and Charlson index of chronic disease 2.2±1.2. Prevalence of hypertension, hyperlipidemia, and psychiatric problems was 68%, 55%, and 73%, respectively. The IVGTT-derived values were (standard Minmod units for all) SI 2.9±1.1, AIRg 449±291, DI 1159±798. Correlation analysis between IVGTT and OGTT-derived indices showed the highest r values for 1/SI: Insulinogenic Index peak [IGIp=(Ip-If)/(Gp-Gf)] r=.590, Ip/Gp r=.589, Ip r=.562 (p≤.0001 for all) while for SI, AIRg and DI the highest r values varied between -.50 and -.42 and included Gm, Gp, AUCGm, and IGIp (p≤0.01 for all). Correlations of 1/SI with widely accepted and commonly used indices were: Matsuda-DeFronzo (2) ISI r=-.13 p=.4, Mari’s (3) OGIS r=-.29 p=.04, and Retnakaran’s (4) ISSI-2 -.21 p=.2. Among other indices only ISSI-2 correlated with AIRg r=.37 and DI r=.31 (p<.05 for both).
Conclusion: Simple measurements and formulas based on OGTT provide accurate and better evaluation of IVGTT-derived indices than more elaborated models in AAM with high disease burden. Further studies in other populations are needed to validate our results.
Nothing to Disclose: BM, AA, YE, EB
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