We read with great interest the recent article by Amin et al. (1), reporting that differences in IGF-1 and androgen concentrations and disruption of glycemic control accompany development of microalbuminuria at puberty. A possible association of diabetic microvascular complications with hormonal abnormalities related to this developmental period is important because risk of microvascular complications increases at puberty, especially in female subjects.
The effect of testosterone on insulin resistance is opposite between men and women; low testosterone concentrations in men (2) but high testosterone concentrations in women (3) favor insulin resistance. Accordingly, the authors might have chosen to evaluate the effect of testosterone for each sex, presenting testosterone and sex hormone-binding globulin (SHBG) concentrations and the free androgen index (FAI) (FAI = testosterone × 100/SHBG) according to sex in Table 2. We also consider the effects of other sex hormones such as estrogen and progesterone on the development of microalbuminuria to be important questions. Low testosterone concentrations promote insulin resistance and atherosclerosis in aging men (2,4). However, low testosterone concentrations may be such a rarity that they have little effect on the development of microalbuminuria in male subjects with type 1 diabetes at puberty.
The authors showed testosterone concentrations and FAI to be higher in female subjects with microalbuminuria. The age-specific normal range and the proportion of subjects with testosterone concentrations and FAI beyond upper normal limits would be important to know because these patients would be especially prone to insulin resistance. Insulin resistance secondary to hyperandrogenism might play a role in the development of microalbuminuria during puberty in female subjects with type 1 diabetes, and these patients should be carefully investigated for early signs of macrovascular and microvascular complications. The authors found that free IGF-1 and testosterone concentrations did not differ between male subjects with and without microalbuminuria, stating that when sexes were considered separately, microalbuminuria was significantly associated with poor glycemic control only among male subjects. Thus, the report’s title should have stressed low IGF-1 and high testosterone in female subjects with type 1 diabetes at puberty who develop microalbuminuria as opposed to normoalbuminuric control subjects.