diabetes mellitus

diabetes mellitus
Name	Diabetes mellitus
Field	Endocrinology
Symptoms	Polyuria, polydipsia, polyphagia, weight loss
Complications	Cardiovascular disease, nephropathy, neuropathy, retinopathy
Onset	Variable
Duration	Chronic
Types	Type 1, Type 2, Gestational, Monogenic

diabetes mellitus

Diabetes mellitus is a group of chronic metabolic disorders characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. It is a leading cause of morbidity and mortality worldwide, linked to cardiovascular disease, renal failure, blindness, and peripheral neuropathy. Recognition, glycemic control, and multidisciplinary management reduce complications and improve outcomes.

Definition and Classification

Diabetes mellitus is classified into major categories including type 1 diabetes, type 2 diabetes, gestational diabetes, and monogenic forms such as maturity-onset diabetes of the young (MODY). Type 1 typically reflects autoimmune-mediated beta cell destruction with onset in childhood or adolescence, while type 2 reflects insulin resistance and relative insulin deficiency associated with metabolic risk factors. Gestational diabetes arises during pregnancy and increases risks for both mother and offspring. International organizations and professional bodies have produced diagnostic criteria and classification schemes used in clinical practice.

Epidemiology and Risk Factors

Global prevalence has risen dramatically during the late 20th and early 21st centuries, with highest burdens in urbanizing regions and aging populations. Risk factors for type 2 diabetes include advancing age, obesity, family history, sedentary lifestyle, and certain ethnic backgrounds; socioeconomic determinants and urbanization influence incidence. Type 1 diabetes incidence varies by region and is associated with genetic predisposition and environmental triggers. Gestational diabetes prevalence is influenced by maternal age, adiposity, and population screening practices.

Pathophysiology

Hyperglycemia in diabetes results from defects in insulin production, insulin action, or both. In autoimmune type 1 diabetes, autoreactive T cells target pancreatic beta cells, leading to insulin deficiency; genetic susceptibility loci influence risk. In type 2 diabetes, peripheral insulin resistance in skeletal muscle and adipose tissue, hepatic glucose overproduction, and progressive beta cell dysfunction interact within a background of lipotoxicity and chronic low-grade inflammation. Gestational diabetes reflects increased insulin resistance during pregnancy combined with inadequate beta cell compensation. Microvascular and macrovascular complications arise from chronic hyperglycemia, advanced glycation end-products, oxidative stress, endothelial dysfunction, and dyslipidemia.

Clinical Presentation and Diagnosis

Patients may present with classic hyperglycemic symptoms—polyuria, polydipsia, polyphagia, and weight loss—or with asymptomatic hyperglycemia detected on screening. Acute metabolic emergencies include diabetic ketoacidosis and hyperosmolar hyperglycemic state. Diagnostic evaluation uses plasma glucose measurements and glycated hemoglobin (HbA1c) thresholds defined by consensus guidelines; oral glucose tolerance testing is applied for equivocal cases and for gestational screening. Diagnostic work-up often includes assessment for autoimmune markers, C-peptide, and evaluation for comorbid cardiometabolic risk factors.

Management and Treatment

Management is multifaceted, including lifestyle modification, glycemic monitoring, pharmacotherapy, and risk factor control. Lifestyle interventions emphasize medical nutrition therapy, weight management, and physical activity; multidisciplinary teams support behavioral change. Pharmacologic options span insulin replacement for absolute deficiency and a range of glucose-lowering agents for type 2 diabetes such as metformin, sulfonylureas, thiazolidinediones, DPP-4 inhibitors, GLP-1 receptor agonists, SGLT2 inhibitors, and insulin analogs. Treatment selection considers efficacy, hypoglycemia risk, effects on weight, cardiovascular and renal outcomes, and patient preferences. Pregnancy and pediatric cases require specialized regimens and monitoring. Device-based care includes continuous glucose monitoring, insulin pumps, and sensor-augmented systems integrated with telemedicine platforms.

Complications and Prognosis

Chronic complications affect microvascular territories—diabetic retinopathy, nephropathy, and neuropathy—and macrovascular systems—coronary artery disease, stroke, and peripheral arterial disease—contributing substantially to mortality and reduced quality of life. Diabetic foot disease with infection and ischemia is a major cause of hospitalization and amputation. Early and sustained glycemic control, blood pressure management, lipid modification, smoking cessation, and screening programs reduce complication risk. Prognosis varies with age at onset, glycemic exposure, comorbidity burden, access to care, and adherence to preventive measures; coordinated public health strategies and advances in therapies aim to improve long-term outcomes.

Category:Endocrine diseases