Fasting indicators of insulin sensitivity: Effects of ethnicity and pubertal status

Abstract

OBJECTIVE - To examine the relationship of fasting indicators of insulin sensitivity with a more invasive measure of insulin sensitivity (frequently sampled intravenous glucose tolerance test [FSIVGTT]) and the effect of Tanner stage and ethnicity on that relationship. RESEARCH DESIGN AND METHODS - Data were analyzed from 149 overweight girls (97 Hispanic and 52 African American) who were either in the early stages of maturation defined by Tanner stages 1 or 2 (52 Hispanic and 18 African American) or in the later stages of maturation defined by Tanner stages 4 and 5 (45 Hispanic and 34 African American). Fasting indicators of insulin sensitivity (IS) included fasting insulin and glucose and the homeostasis model assessment of insulin resistance (HOMA-IR). IS was derived froman FSIVGTT with minimal-modeling. RESULTS - In Tanner stages 1 and 2, all fasting indicators were significantly associated with IS: (fasting insulin: r = -0.67, P<0.01; HOMA: r =-0.66, P<0.01) with no significant influence of ethnicity on these relationships. In Tanner stages 4 and 5, however, all fasting indicators were associated with IS in African American girls (fasting insulin: r = -0.55, P< 0.01; HOMA: r = -0.47, P< 0.01), but none of the indicators were significantly associated with IS in Hispanic girls. CONCLUSIONS - Fasting indicators were reflective of IS for girls in Tanner stages 1 and 2, regardless of ethnicity and may provide a clinical measure of future risk for type 2 diabetes. In the latter stages of maturation, however, more invasive measures are warranted to adequately determine IS in clinical practice. © 2011 by the American Diabetes Association.