Using a modification of the glucose clamp technique, we have studied the efficacy of commonly used foods to correct hypoglycemia in insulin-dependent diabetics. After lowering the plasma glucose level to 55 mg/dL at a steady-state plasma free insulin concentration of about 50 microU/mL, patients were fed 20 g of carbohydrate as milk, orange juice, or D-glucose or 40 g of carbohydrate as orange juice. The data indicate that 20 g of carbohydrate as D-glucose corrects hypoglycemia without rebound hyperglycemia. In an outpatient setting, this treatment also proved effective in spontaneous episodes of hypoglycemia. We conclude that (1) the D-glucose content of the ingested carbohydrate is an important determinant of the glycemic response, and (2) at times of moderately severe hypoglycemia, ingestion of 20 g of D-glucose provides an effective glycemic response for periods of at least 40 minutes. In view of these data, a table is provided listing some common sources of 20 g of D-glucose.