Two new indexes of DI and BCF, parallel to HOMA basal indexes, based on analysis of 1313 individuals subjected to 75 Gm OGTT are proposed. Glucose and insulin Area Under Curve (AUC) values were calculated using trapezoidal rule. OGTT Insulin Secretion (Isec) was calculated using ’AUCins/AUCglu’ and insulin sensitivity (Isen) by using ’(1/(AUCins * AUCglu)’ formula which was derived by omitting basal values from Matsuda Index. Calculation of Disposition Index (OGTT-DI) i.e., ISec*ISen, was found proportional to ’1/(AUCglu)^2’, as the ’AUCins’ values in denominator and numerator were cross-cancelled. Considering other non-insulin dependent glucose disposal variables as ’constant’, a new index of BCF function, OGTT-B, was defined and derived using ’(OGTT-DI Test/OGTT-DI Normal) * 100’ formula. This resulted in a final equation as ’[{(AUCglu normal) ^2/(AUCglu-test) ^2} * 100]’. Normal AUCglu, a population specific variable, was determined from 10 normoglycemic non-obese individuals and was ’241’. Fourteen categories of dysglycemia were defined based on glucose, insulin, HOMA-IR and Matsuda index. When compared, OGTT-DI showed more consistent linear relationship to evolving dysglycemia categories than other BCF indexes such as HOMA-DI, oral-DI and ISSI-2. (Figure below). Being independent of Insulin and BMI levels, OGTT-DI and OGTT-B are simple and low cost BCF indexes which will be useful in staging and managing dysglycemia.
S.N. Shinde: None. R.S. Shinde: None. A.S. Joshi: None.
