HNF1A and diabetes mellitus: Gandica et al. found HNF1A and GCK mutations in 5 of 10 (50%) subjects who met a clinical diagnosis of T1DM and at least 2 of the following 3 criteria: negative autoantibodies to at least 1 of either GAD65, IAA, or ICA, hemoglobin A1c level (HbA1c) <7% with an insulin requirement of <0.5 U/kg/day, or at least 3 consecutive generations of family members with diabetes 8.