Diabetes Mellitus (DM) is a chronic, progressive metabolic disorder characterized by persistent hyperglycemia due to defects in insulin secretion, insulin action, or both. It affects millions globally, posing a significant public health challenge with high morbidity and mortality rates. This review discusses the classification of DM, including Type 1, Type 2, gestational diabetes, and other rare forms. Key risk factors such as genetic predisposition, obesity, age, and lifestyle choices are highlighted as contributors to the rising global incidence of DM. The article also explores the complications of uncontrolled diabetes, including microvascular and macrovascular issues, as well as psychological burdens. Modern diagnostic techniques, such as the Hemoglobin A1c test and oral glucose tolerance test, are explained. Treatment strategies, from lifestyle interventions to pharmacological treatments like insulin therapy and GLP-1 receptor agonists, are presented to illustrate comprehensive management of the disease. The review emphasizes the importance of early diagnosis and long-term glucose control to prevent complications and improve patient outcomes. DM is classified into four main types: Type 1 Diabetes (T1DM), Type 2 Diabetes (T2DM), Gestational Diabetes Mellitus (GDM), and other specific types. T1DM is an autoimmune condition where the body's immune system attacks insulin-producing beta cells, leading to insulin deficiency. T2DM is the most prevalent form, characterized by insulin resistance and a decline in insulin production. GDM develops during pregnancy and typically resolves after childbirth. Other specific types include genetic defects in beta-cell function, insulin action, and diseases of the exocrine pancreas. The global prevalence of DM is increasing, with over 537 million adults affected as of 2021, projected to rise to 783 million by 2045. Risk factors include genetic predisposition, obesity, physical inactivity, age, dietary habits, ethnicity, and a history of gestational diabetes. Complications of DM include microvascular issues like diabetic retinopathy, nephropathy, and neuropathy, as well as macrovascular complications such as cardiovascular disease and diabetic foot. Other complications include infections, inflammation, and mental health issues. Diagnosis involves tests such as fasting plasma glucose, oral glucose tolerance test, Hemoglobin A1c, and random plasma glucose. Treatment includes lifestyle changes, medication, and monitoring of blood glucose levels. Pharmacological treatments include insulin therapy and oral medications like metformin and GLP-1 agonists. Monitoring is essential for effective management. The review concludes with the importance of early diagnosis and long-term glucose control to prevent complications and improve patient outcomes.Diabetes Mellitus (DM) is a chronic, progressive metabolic disorder characterized by persistent hyperglycemia due to defects in insulin secretion, insulin action, or both. It affects millions globally, posing a significant public health challenge with high morbidity and mortality rates. This review discusses the classification of DM, including Type 1, Type 2, gestational diabetes, and other rare forms. Key risk factors such as genetic predisposition, obesity, age, and lifestyle choices are highlighted as contributors to the rising global incidence of DM. The article also explores the complications of uncontrolled diabetes, including microvascular and macrovascular issues, as well as psychological burdens. Modern diagnostic techniques, such as the Hemoglobin A1c test and oral glucose tolerance test, are explained. Treatment strategies, from lifestyle interventions to pharmacological treatments like insulin therapy and GLP-1 receptor agonists, are presented to illustrate comprehensive management of the disease. The review emphasizes the importance of early diagnosis and long-term glucose control to prevent complications and improve patient outcomes. DM is classified into four main types: Type 1 Diabetes (T1DM), Type 2 Diabetes (T2DM), Gestational Diabetes Mellitus (GDM), and other specific types. T1DM is an autoimmune condition where the body's immune system attacks insulin-producing beta cells, leading to insulin deficiency. T2DM is the most prevalent form, characterized by insulin resistance and a decline in insulin production. GDM develops during pregnancy and typically resolves after childbirth. Other specific types include genetic defects in beta-cell function, insulin action, and diseases of the exocrine pancreas. The global prevalence of DM is increasing, with over 537 million adults affected as of 2021, projected to rise to 783 million by 2045. Risk factors include genetic predisposition, obesity, physical inactivity, age, dietary habits, ethnicity, and a history of gestational diabetes. Complications of DM include microvascular issues like diabetic retinopathy, nephropathy, and neuropathy, as well as macrovascular complications such as cardiovascular disease and diabetic foot. Other complications include infections, inflammation, and mental health issues. Diagnosis involves tests such as fasting plasma glucose, oral glucose tolerance test, Hemoglobin A1c, and random plasma glucose. Treatment includes lifestyle changes, medication, and monitoring of blood glucose levels. Pharmacological treatments include insulin therapy and oral medications like metformin and GLP-1 agonists. Monitoring is essential for effective management. The review concludes with the importance of early diagnosis and long-term glucose control to prevent complications and improve patient outcomes.