Understanding Diabetes Mellitus: Definition and Classification

Posted on Mar 19, 2025 in Medicine

Diabetes Mellitus: Definition

Diabetes mellitus is a group of metabolic disorders sharing the common feature of hyperglycaemia. Hyperglycaemia in diabetes results from defects in insulin secretion, insulin action, or both. The chronic hyperglycaemia and attendant metabolic dysregulation may be associated with secondary damage in multiple organ systems, especially the kidney, eyes, nerves, and blood vessels.

Classification of Diabetes Mellitus

Although all forms of diabetes mellitus share hyperglycaemia as a common feature, the underlying abnormalities involved in the development of hyperglycaemia vary widely.

  • Type 1 Diabetes: An autoimmune disease characterized by pancreatic β cell destruction and an absolute deficiency of insulin. It accounts for approximately 5% to 10% of all cases.
  • Type 2 Diabetes: Caused by a combination of peripheral resistance to insulin action and an inadequate secretory response by the pancreatic β cells (“relative insulin deficiency”). Approximately 90% to 95% of diabetic patients have type 2 diabetes.

Etiopathogenesis of Type 1 Diabetes Mellitus

Also called Insulin-Dependent Diabetes Mellitus (IDDM). It is an autoimmune disease in which islet destruction is caused primarily by immune effector cells reacting against endogenous β-cell antigens. Type 1 diabetes requires insulin for survival; without insulin, individuals develop serious metabolic complications such as ketoacidosis and coma. It usually occurs in children.

Type 2 Diabetes Mellitus

Also called Insulin-Independent Diabetes Mellitus (IIDDM). Type 2 diabetes is a complex disease that involves an interplay of genetic and environmental factors and a proinflammatory state. Unlike type 1 diabetes, there is no evidence of an autoimmune basis. It usually occurs in middle age.

Pharmacological Managements

  1. Insulin
    • Long-acting: Ex- Insulin degludec, Insulin glargine.
    • Intermediate-acting: Ex- Insulin Zinc suspension
    • Short-acting: Ex- Biphasic Insulin.
    • Rapid-acting: Ex- insulin aspart, Insulin lispro