Which disease is often split into groups called Type 1 and Type 2?

Diabetes mellitus, commonly referred to simply as diabetes, is a metabolic disease that causes high blood sugar. Type 1 diabetes is an autoimmune disease. The immune system attacks and destroys cells in the pancreas, where insulin is made. It’s unclear what causes this attack. Type 2 diabetes occurs when your body becomes resistant to insulin, and sugar builds up in your blood. It’s the most common type—about 90% to 95% of people living with diabetes have type 2. There is also Gestational diabetes, which is high blood sugar during pregnancy caused by insulin-blocking hormones produced by the placenta.

Source: Healthline