Even when diabetes is managed very carefully, the medications used to treat diabetes can result in episodes of drug-induced hypoglycemia. Medication-induced hypoglycemia can also be caused by improper management of diabetes. Missing meals, overexertion, and intentional or unintentional overdose of medications used to treat the condition can all cause blood glucose levels to drop.

Medications that can cause hypoglycemia include insulin and sulfonylureas. Newer drugs for diabetes such as metformin (Glucophage) can also cause hypoglycemia when used in combination with sulfonylureas. The condition may also occur when a nondiabetic individual takes insulin or a sulfonylurea drug.

Other drugs such as pentamidine can also occasionally induce hypoglycemia. Rarer causes of low blood glucose include the use of quinidine, quinine, beta-blocker drugs, MAO inhibitors (a type of antidepressant), Bactrim (an antibiotic), and haloperidol.

Regardless of cause, hypoglycemia is defined by what physicians call "Whipple's triad":

1. Symptoms and signs of hypoglycemia including anxiety, shakiness, palpitations, sweating, nightmares, irritability, and hunger
2. Plasma glucose less than 45 mg/dL
3. Reversal of symptoms with administration of glucose

Symptoms of acute hypoglycemia may be more pronounced than for chronic hypoglycemia. Symptoms of chronic hypoglycemia can include ataxia (movement difficulties), convulsions, and altered consciousness.

Signs of hypoglycemia may include:

• tremulousness
• tachycardia (fast heartbeat)
• diaphoresis (sweating)
• ataxia (movement problems)
• convulsions
• confusion
• lethargy
• coma

Tests may show:

• low plasma glucose
• in cases where people without diabetes have taken drugs for the condition:
  • elevated serum insulin with low serum C-peptide
  • urine positive for sulfonylureas