Diabetes mellitus (DM) or better known as simply diabetes is a group of metabolic diseases in which high blood sugar levels are maintained over a prolonged period. Diabetes mellitus (DM) or better known as simply diabetes is a group of metabolic diseases in which high blood sugar levels are maintained over a prolonged period. Diabetes mellitus (DM) or better known as simply diabetes is a group of metabolic diseases in which high blood sugar levels are maintained over a prolonged period. Diabetes mellitus (DM) or better known as simply diabetes is a group of metabolic diseases in which high blood sugar levels are maintained over a prolonged period.