Is Type 2 Diabetes Mellitus one Disease?

This review aims to describe the four subtypes or clusters of Type 2 DM. We believe that differentiating these subtypes based on clinical and laboratory features—such as glutamic acid decarboxylase antibodies (GAD), age at onset, HbA1c, body mass index (BMI), and measures of insulin resistance and secretion—can help characterize them. The main goal of identifying these clusters is to improve treatment personalization and prevent complications that vary among these groups. The severe insulin-deficient group at diagnosis resembles Type 1 diabetes but lacks autoantibodies against beta cells and has different genetic markers. Microvascular complications like diabetic neuropathy and retinopathy are most common in this subtype, along with cardiovascular issues. Insulin therapy should be started early in this group. The insulin-resistant subtype is associated with the highest risk of diabetic nephropathy. Efforts to reduce insulin resistance and protect kidney function are essential in this cluster. The mild obesity-related and mild age-related subtypes usually have a lower risk of complications and respond well to lifestyle changes and weight loss. Recognizing these subtypes of Type 2 DM allows for a personalized approach to managing the disease.