Nocturnal hypoglycemia and the effect on sleep in patients with type 2 diabetes

The main objective of this study was to determine the impact of nocturnal hypoglycemia on sleep patterns in patients with type 2 diabetes. The authors concluded that nocturnal hypoglycemia caused a decrease in a patient's ability to wake up and respond to episodes of low blood sugar levels.

Nocturnal hypoglycemia (NH) is a condition in diabetes that rarely shows symptoms until after it has occurred. NH occurs when blood sugar levels decrease during the night while the person is asleep. lt is most common in patients who treat their diabetes with insulin. Signs that NH have occurred include headaches, damp sheets from sweating and an unusual lack of energy.

Almost 50% of all hypoglycemic events occur during the night. These may cause convulsions and impair body functioning. In severe cases they could lead to comas or heart attacks if not managed correctly. This can be managed by eating before bed and measuring blood sugar levels before and during the night to ensure sugar levels remain stable. It is not clear whether or how NH affects sleep patterns. 

The aim of this study was to determine the effect of NH on sleep patterns in patients with type 2 diabetes. 

26 insulin-naive patients were used in this randomized study. Patients underwent three monitored night visits. The first night was for the patients to adapt to the study situation. One night was to observe normoglycemia (normal level of sugar in the blood). Normal blood sugar levels were maintained using a hyperinsulinemic glucose clamp (maintained using a continuous infusion of glucose). Blood sugar levels were maintained at 5.0 – 7.0 for the night. The other night was to observe hypoglycemia. This was managed by shutting off the glucose clamp until the target blood sugar levels of 2.7 – 2.8 were reached and maintained for 15 minutes.

During the first 0-4 hours, no difference was observed in sleeping patterns or awakenings in the hypoglycemic night. However, the rate of awakening was 27% lower during hours 4-8 compared to the normoglycemic night. Overall, night awakenings were 20% lower during the 0-8 hour period on the hypoglycemic night. Total sleep time was longer during the hypoglycemic night. 

The authors concluded that nocturnal hypoglycemia caused a decrease in a patient's ability to wake up and respond to episodes of low blood sugar levels.