Our data provide some evidence that ARNT variants may alter insulin secretion and that ARNT gene variants may alter transcript levels, but our findings are not compatible with the dramatic differences in transcript levels observed by Gunton et al. We suggest that such striking reductions in ARNT transcript levels in the diabetic pancreas are unlikely to be caused by genetic variants and thus not the direct cause of the insulin secretory defect that occurs early in type 2 diabetes and progresses throughout the disease. Here, ARNT is linked to type 2 diabetes mellitus.