**Core Concept**
Quinine, a potent antimalarial drug, can induce hypoglycemia as a side effect, especially in patients with falciparum malaria who have underlying metabolic disturbances. This is due to quinine’s interference with glucose metabolism and its ability to increase insulin secretion or reduce hepatic glucose production.

**Why the Correct Answer is Right**
Quinine causes hypoglycemia by inhibiting gluconeogenesis in the liver and enhancing insulin release from pancreatic beta cells. In malaria, especially severe falciparum malaria, the body’s metabolic stress and increased consumption of glucose predispose patients to hypoglycemia. When quinine is administered, it exacerbates this by further lowering blood glucose levels, leading to symptoms like sweating and palpitations—classic signs of hypoglycemia.

**Why Each Wrong Option is Incorrect**
Option A: Cinchonism refers to symptoms like tinnitus, headache, and visual disturbances due to quinine toxicity, not sweating and palpitations. It is not associated with hypoglycemia.
Option B: Hyperglycemia would cause polyuria, polydipsia, and dehydration, not sweating and palpitations. Quinine does not elevate blood glucose.
Option D: Hypokalemia may occur with quinine, but it typically presents with muscle weakness, arrhythmias, and ECG changes—not sweating and palpitations.

**Clinical Pearl / High-Yield Fact**
Quinine-induced hypoglycemia is a well-known adverse effect, especially in children and during severe malaria episodes. Always monitor blood glucose in patients on quinine therapy, and treat hypoglycemia promptly with glucose administration.

✓ Correct Answer: C. Hypoglycemia