Diabetes mellitus is a global health crisis with rising prevalence, particularly in the Western Pacific region, where 37.5% of people have diabetes. The Middle East and North Africa have the highest incidence in adults. Diabetes is classified into several types, including type 1, type 2, gestational diabetes, and monogenic diabetes. Type 1 diabetes is autoimmune, caused by the destruction of pancreatic beta cells, and is more common in children and adolescents. It is associated with genetic factors and autoantibodies. Type 2 diabetes is more prevalent in adults and is linked to lifestyle and genetic factors. Monogenic diabetes is caused by mutations in a single gene and includes neonatal diabetes and maturity-onset diabetes of the young (MODY). Other forms include exocrine pancreas disease, hormone-related diabetes, and genetic syndromes. Diagnosis is based on fasting plasma glucose, 2-hour oral glucose tolerance test, HbA1c, and random plasma glucose. HbA1c is increasingly used for diagnosis due to its advantages over traditional methods. Genetic factors play a significant role in the development and complications of diabetes, including nephropathy, retinopathy, and cardiovascular disease. Understanding the molecular genetics of diabetes can improve diagnosis, treatment, and prevention of complications. Despite advances, the exact mechanisms of diabetes development remain unclear, and further research is needed to enhance early detection and management. The epidemic of diabetes requires urgent attention to reduce its impact on global health.Diabetes mellitus is a global health crisis with rising prevalence, particularly in the Western Pacific region, where 37.5% of people have diabetes. The Middle East and North Africa have the highest incidence in adults. Diabetes is classified into several types, including type 1, type 2, gestational diabetes, and monogenic diabetes. Type 1 diabetes is autoimmune, caused by the destruction of pancreatic beta cells, and is more common in children and adolescents. It is associated with genetic factors and autoantibodies. Type 2 diabetes is more prevalent in adults and is linked to lifestyle and genetic factors. Monogenic diabetes is caused by mutations in a single gene and includes neonatal diabetes and maturity-onset diabetes of the young (MODY). Other forms include exocrine pancreas disease, hormone-related diabetes, and genetic syndromes. Diagnosis is based on fasting plasma glucose, 2-hour oral glucose tolerance test, HbA1c, and random plasma glucose. HbA1c is increasingly used for diagnosis due to its advantages over traditional methods. Genetic factors play a significant role in the development and complications of diabetes, including nephropathy, retinopathy, and cardiovascular disease. Understanding the molecular genetics of diabetes can improve diagnosis, treatment, and prevention of complications. Despite advances, the exact mechanisms of diabetes development remain unclear, and further research is needed to enhance early detection and management. The epidemic of diabetes requires urgent attention to reduce its impact on global health.