Normal Insulin Sensitivity During the Late Preclinical Stage of Type 1 Diabetes

In most cases, type 1 diabetes is the late consequence of a β-cell autoimmune destruction leading to absolute insulin deficiency (1). At onset of clinical diabetes, β-cell mass is thought to be reduced by 80–90% (2), and 73% of adult patients have ketosis or ketoacidosis at diagnosis (3). Patients with type 1 diabetes have major defects in insulin sensitivity at diagnosis of overt diabetes (4–8). However, the fact that pre-diabetic patients can maintain normal blood glucose levels in spite of dramatically low insulin secretory capacities suggests that their insulin sensitivity is normal. Here we report that insulin sensitivity, measured by the glucose clamp method in nine patients, remains normal even during the very late preclinical stage of type 1 diabetes. None of these patients …