GAD1 and type 1 diabetes mellitus: Thirteen patients with type 1 diabetes (T1D) had a history of positive antibodies, including GAD-ab and/or IA2-ab and severely impaired insulin secretion (serum C-peptide immunoreactivity < 0.6 ng/mL and/or 24-h urine collection C-peptide immunoreactivity < 20 μg/day), and were treated with a basal-bolus injection of insulin.