The recent report by Strowig and Raskin (1) raises the intriguing issue as to whether some type 1 diabetic patients may benefit from a supplementary insulin sensitization approach to their management. As our and other studies have shown that an estimate of insulin sensitivity (eGDR) is strongly predictive of mortality (2), coronary artery disease events (3), coronary calcification (4), and overt nephropathy (5) in type 1 diabetes, we would strongly endorse further pursuit of this approach.
The eGDR measure is based on a regression equation (with terms for waist-to-hip ratio, hypertension status, and HbA1c, i.e., eGDR = 24.39 − 12.97 [waist-to-hip ratio] − 3.39 [hypertension] − 0.60 [HbA1c]) derived from 24 hyperinsulinemic-euglycemic clamp studies and has an r2 of 0.63 for measured glucose disposal rate (6). As eGDR might therefore be a useful identifier of those who would benefit from thiazolidinedione therapy, it would be helpful to know if eGDR predicted response to rosiglitazone therapy in terms of HbA1c in the Strowig and Raskin (1) study. In addition, was there any difference in change of waist circumference (or waist-to-hip ratio) by treatment group, consistent with the observation (7) that weight gain with rosiglitazone is mainly peripheral rather than central? Finally, it is notable that lipid concentrations were not generally affected by rosiglitazone therapy in contrast to blood pressure. This is similar to our eGDR studies wherein lipids did not help to predict glucose disposal rate, but hypertension status did (6). Do these dual observations thus suggest that in type 1 diabetes insulin resistance is more strongly linked to blood pressure than to lipids?
References
T.J.O. has received grant/research support from GlaxoSmithKline.
