GAD1 and diabetes mellitus: BMI, and GAD and IA-2A antibodies change modestly over time in adult onset diabetes, with previous research suggesting an approximately 18% lower combined GADA and IA-2A prevalence after 13.5 years diabetes duration in this age group,43 and BMI having higher discrimination for diabetes classification when measured at diagnosis.44 The potential impact on the results of BMI and islet autoantibodies having been measured some years post-diagnosis is that the predictions may be under-estimated.