Progression from normal glucose tolerance to type 2 diabetes in a young girl: longitudinal changes in insulin sensitivity and secretion assessed by the clamp technique and surrogate estimates.

The pathophysiology of type 2 diabetes (T2DM) involves insulin resistance and relative insulin deficiency in at-risk youth. We-report longitudinal changes in insulin sensitivity and secretion in a high-risk African-American youth with obesity and polycystic ovary syndrome who progressed from normal glucose tolerance to impaired glucose tolerance to T2DM within 5 yr. This report demonstrates that in our patient: (i) insulin resistance was the pre-existing abnormality, but it was the marked decline in insulin secretion which led to T2DM and (ii) surrogate estimates of insulin sensitivity using fasting glucose and insulin concentrations were not reliable indices in reflecting the changes in in vivo insulin sensitivity in this case.