Here we examined whether the same variant showed similar effects on HOMA2-B at 6, 12 and 24 years, and found that the KCNQ1 variant showed significant parent-of-origin specific associations at 12 and 24 years, with the previously reported type 2 diabetes risk and insulin secretion-lowering maternal allele C lowering (and the alternate T allele increasing) HOMA2-B at 12 and 24 years. Here, KCNQ1 is linked to type 2 diabetes mellitus.