Diabetes Mellitus

Diabetes Mellitus (DM) is a group of metabolic disorders characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action, or both, leading to disturbances in carbohydrate, fat, and protein metabolism.

Definition

Epidemiology

Affects over 500 million people worldwide
Type 2 Diabetes accounts for 90–95% of all cases
Rising prevalence due to obesity, sedentary lifestyle, and aging population
Common in middle-aged and older adults, but increasingly seen in youth
Higher prevalence in South Asians, African Americans, and Hispanics
Strong genetic and environmental components
Leading cause of blindness, kidney failure, and non-traumatic lower limb amputation globally

Etiology

Type 1 Diabetes: autoimmune destruction of pancreatic beta cells
Type 2 Diabetes: insulin resistance and progressive beta-cell dysfunction
Genetic predisposition and family history
Obesity, physical inactivity, and high-calorie diets
Gestational diabetes and metabolic syndrome
Pancreatic diseases (chronic pancreatitis, pancreatic cancer)
Drug-induced (steroids, thiazides, antipsychotics)

Pathophysiology

Inadequate insulin secretion or impaired insulin action leads to hyperglycemia
Increased hepatic glucose output and decreased glucose uptake by tissues
Lipolysis and proteolysis lead to elevated free fatty acids and muscle wasting
Chronic hyperglycemia causes advanced glycation end-product (AGE) formation
Microvascular damage (retinopathy, nephropathy, neuropathy)
Macrovascular complications (atherosclerosis, CAD, stroke, PAD)
Oxidative stress and inflammation play key roles in long-term complications