Median time to diabetes presentation after the start of ICI treatment was 12.3 weeks but ranged from 1 to 67.2 weeks. Half of the cases presented in diabetic ketoacidosis (DKA). Patients had upward trending hyperglycemia and most had diabetes symptoms for a while before diagnosis. They presented with a blood glucose above 250 mg/dL, and more than half above 500 mg/dL. Median hemoglobin A1c at presentation was 8%, but ranged up to 12.5%.
Every patient required insulin, including the six that discontinued ICIs after developing diabetes. Diabetes resolved in just one patient at 10.2 months; she presented with DKA.
There were no obvious predisposing factors. None of the patients had histories of type 1 diabetes or other autoimmune disease. Five patients had well-controlled type 2 diabetes prior to ICI initiation; four had prediabetes. Some had family members with type 2 diabetes, but not type 1. Four had prior ICI exposure. Just three patients were on concomitant steroids.
A few patients also developed thyroid or pituitary dysfunction, which are more common side effects of ICIs.