Diabetes mellitus results from the abnormal secretion or action of what substance?

• A. Lactose
• B. Insulin
• C. Glucose
• D. Sucrose

Answer: (B)

Insulin, the hormone produced by pancreatic beta cells, regulates how glucose moves from the bloodstream into most body cells. Diabetes mellitus results from abnormal secretion or action of insulin, meaning there isn’t enough insulin or the body's cells don’t respond properly to it. When that happens, glucose stays in the blood instead of entering cells for energy, causing high blood glucose levels and the characteristic symptoms. The other substances listed—lactose, glucose, and sucrose—are sugars and nutrients, not hormones; they don’t drive the disease the way impaired insulin production or insulin resistance does.