Prevention of hypoglycemia is an important strategy for glycemic management in patients with type 1 diabetes mellitus (T1D). Hypoglycemia is difficult to recognize at night while sleeping, particularly when using multiple daily injection (MDI) insulin therapy rather than sensor-augmented insulin-pump therapy. Therefore, it is possible that patients with T1D are at higher risk of nocturnal hypoglycemia when insulin is administered using an MDI regimen. We investigated nocturnal hypoglycemia in 50 pediatric patients with T1D on MDI insulin therapy using data from an intermittently scanned continuous glucose monitoring (isCGM) system. Hypoglycemia was observed on 446 of the 1,270 nights studied. Most of the hypoglycemic episodes were severe (blood glucose <54 mg/dL). On nights when hypoglycemia occurred, the blood glucose concentrations measured using finger-stick blood glucose monitoring (FSGM) before sleep and the next morning were lower than nights when hypoglycemia did not occur. However, few values were below the normal blood glucose range, suggesting that FSGM alone may be insufficient to detect nocturnal hypoglycemia. Approximately 7% of time was spent below the normal glucose range during the 10 hours from 21:00 to 7:00 the next morning. This result suggests that the patients on MDI insulin therapy could end up spending more time in hypoglycemia than is recommended by the American Diabetes Association (time below range <4.0% of time per day). Monitoring glucose levels overnight using an isCGM sensor may improve glycemic management via automatic detection of blood glucose peaks and troughs.