Insulin downregulates hepatic production of sex hormone–binding globulin (SHBG), which in turn influences sex hormone bioavailability. The effects of childhood-onset diabetes and insulin resistance in nondiabetic individuals on SHBG and testosterone in children and young adults are poorly understood.RESEARCH DESIGN AND METHODS
Individuals with diabetes diagnosed at <18 years of age (n = 48) and their siblings without diabetes (n = 47) were recruited for the Chicago Childhood Diabetes Registry Family Study. SHBG and total and free testosterone were measured. Participants ranged in age from 10 to 32 years; 39% were non-Hispanic white. The majority of individuals with diabetes had the classic type 1 phenotype (75%), while the remainder exhibited features of type 2 or mixed diabetes; 96% were treated with insulin.RESULTS
SHBG and total testosterone were higher in male subjects with diabetes compared with those in male siblings. Elevated SHBG was associated with the absence of endogenous insulin independent of sex; elevated total testosterone was similarly associated with the absence of C-peptide for male subjects only. Diabetes type and treatment were unrelated. In those without diabetes, greater insulin resistance had a small, nonsignificant association with lower SHBG and higher free testosterone.CONCLUSIONS
SHBG and total testosterone appear to be higher in male children and young adults with diabetes compared with nondiabetic male siblings, which is apparently related to the absence of endogenous insulin. This may have implications for sex hormone–dependent processes across the lifespan in male individuals diagnosed with diabetes as children.