Comparison of insulin sensitivity indices for detection of double diabetes in Indian adolescents with type 1 diabetes.

OBJECTIVES: The role of insulin sensitivity (IS) in the development and progression of metabolic syndrome (MS) in subjects with type-1 diabetes (T1D) is being increasingly recognized. As patients with T1D lack endogenous insulin secretion, measurement of insulin concentration by immunoassay or by indices such as homeostasis model of assessment for insulin resistance (HOMA-IR) is not helpful in assessing IS. Hence, some equations have been developed and validated against data from euglycemic-hyper-insulinemic clamp tests (the gold standard) to estimate IS. 1) To assess IS using available equations (EDC, SEARCH and CACTI) and relationship of IS with MS and microalbuminuria in adolescents with T1D, (2) To compare the predictive value of these equations for detection of MS and derive a cut-off to predict the future risk of development of MS and microalbuminuria and (3) To identify the most accurate non-invasive and easy-to-use equation for detecting patients with double diabetes (DD) in a clinical setting. METHODS: This cross-sectional study included 181 adolescents aged 12-18 years with T1D. Demographic data and laboratory measurements were performed using standard protocols. IS was calculated using following equations:(1) EDC=24.31-12.22×(WHR)-3.29×(hypertension)-0.57×(HbA1c), (2) SEARCH=exp(4.64725-0.02032(waist)-0.09779(HbA1c)-0.00235(Triglycerides), (3)CACTI-exA=exp(4.1075-0.01299×(waist)-1.05819×(insulin dose)-0.00354×(Triglycerides)-0.00802×(DBP)). RESULTS: IS determined by all three methods had significant negative correlation (p<0.05) with MS as well as with microalbuminuria. The cut-off value of 5.485 mg/kg/min by SEARCH method for determining IS had the highest sensitivity and specificity in identifying MS. CONCLUSIONS: IS by SEARCH equation may be used in routine clinical practice to detect DD in Indian adolescents with T1D at risk of developing metabolic as well as microvascular complications.