Diabetes Mellitus Type I is an autoimmune disease where the body destroys insulin-producing beta cells in the pancreas, resulting in a lack of insulin production and high blood sugar levels. It is usually diagnosed in children and young adults and requires daily insulin injections or an insulin pump to manage blood sugar levels. Diabetes Mellitus Type II is a metabolic disorder where the body becomes resistant to insulin or doesn't produce enough insulin to maintain normal blood sugar levels. It is most commonly diagnosed in adults and can often be managed with lifestyle changes, oral medications, or insulin therapy.