Diabetes is a chronic lifestyle disorder that affects millions of people worldwide. Diabetes is a condition where the body does not produce sufficient insulin or does not use it efficiently. Insulin resistance in diabetes or obesity causes the pancreatic β-cells to increase the insulin output. Diabetes occurs in multiple forms, including type 1, type 2, type 3 and gestational. Type 2 diabetes accounts for ∼90-95% of total affected population and is associated with both impaired insulin production by the β-cells of the pancreas and impaired insulin release in response to high blood glucose levels. Diabetes is tightly linked with genetic mutations and genetic and lifestyle activities, including diet and exercise. Recent epidemiological studies established a close link between the diabetes and progression to Alzheimer's disease. This article summarizes various molecular mechanisms involved in the developments of diabetes, including biochemical characteristics, genetic and molecular links with Alzheimer's disease, β-cell function, and factors associated with diabetes. This will help us in the development of novel therapeutic strategies targeting AD in future.