Yes. Lantus (insulin glargine) can cause hypoglycemia. Like other insulins, it lowers blood glucose, and hypoglycemia is its most common adverse effect.

Although Lantus is long-acting and has a relatively flat, peakless action profile, low glucose can still occur, particularly with:

Harrison's describes hypoglycemia as the major limiting adverse effect of insulin therapy. Lantus is a basal insulin, so its long duration may mean recovery from a low glucose can sometimes be prolonged.

Symptoms include sweating, tremor, palpitations, hunger, dizziness, confusion, or drowsiness. If the person is conscious, take fast-acting carbohydrate and recheck glucose in about 15 minutes. Severe confusion, unconsciousness, or inability to swallow requires urgent emergency treatment.

The FDA Lantus label likewise states that hypoglycemia is the most common adverse reaction to insulin, including Lantus, and notes that its prolonged action can delay recovery from hypoglycemia.