True about sulfonylureas is –
**Core Concept**
Sulfonylureas are a class of medications used in the management of type 2 diabetes mellitus. They work by stimulating the release of insulin from the pancreatic beta cells, thereby increasing glucose utilization and reducing blood glucose levels.
**Why the Correct Answer is Right**
Sulfonylureas bind to and block the ATP-sensitive potassium channels (K_ATP channels) in the pancreatic beta cells. This blockade inhibits the efflux of potassium ions, leading to membrane depolarization and opening of voltage-dependent calcium channels. The influx of calcium ions triggers the exocytosis of insulin-containing granules, resulting in increased insulin secretion. This mechanism is specific to sulfonylureas and is responsible for their therapeutic effects in diabetes management.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because sulfonylureas do not primarily work by inhibiting alpha-glucosidase enzymes, which are involved in carbohydrate digestion.
**Option B:** This option is incorrect because sulfonylureas do not primarily work by activating beta-3 adrenergic receptors, which are involved in lipolysis and thermogenesis.
**Option C:** This option is incorrect because sulfonylureas do not primarily work by inhibiting the reabsorption of glucose in the proximal convoluted tubule of the kidneys, which is a mechanism of action for certain other classes of antidiabetic medications.
**Clinical Pearl / High-Yield Fact**
Sulfonylureas can cause hypoglycemia as a side effect, especially when used in combination with other antidiabetic medications or in patients with renal or hepatic impairment. It is essential to monitor patients on sulfonylureas for signs of hypoglycemia, such as dizziness, confusion, and tremors.
**Correct Answer:** D.