The Impact of Nocturnal Hypoglycemia on Sleep in Subjects With Type 2 Diabetes.

OBJECTIVE: The aim of this trial was to investigate the impact of nocturnal hypoglycemia on sleep patterns (assessed by polysomnography) and counterregulatory hormones.

RESEARCH DESIGN AND METHODS: In this single-blinded, crossover trial, 26 subjects with type 2 diabetes attended two experimental night visits (one normoglycemic and one hypoglycemic) in randomized order. Plasma glucose (PG) levels were controlled by hyperinsulinemic glucose clamping. On the hypoglycemic night, hypoglycemia was induced after reaching sleep stage N2 by turning off glucose infusion until the PG target of 2.7-2.8 mmol/L was reached and maintained for 15 min. Thereafter, subjects were brought back to normoglycemia for the rest of the night. On the normoglycemic night, PG was maintained at 5.0-7.0 mmol/L throughout the night.

RESULTS: During the first 4 h of sleep (0-4 h; after reaching sleep stage N2), no difference between experimental nights was observed in the rate of electroencephalography-identified arousals or awakenings, but the rate of awakenings was 27% lower during 4-8 h and 20% lower during 0-8 h on the hypoglycemic night than on the normoglycemic night (both statistically significant). Total sleep time tended to be longer on the hypoglycemic night (observed means 366 vs. 349 min, P nonsignificant). Statistically significantly higher counterregulatory hormonal responses (adrenaline, growth hormone, and cortisol) to hypoglycemia were observed compared with normoglycemia.

CONCLUSIONS: Nocturnal hypoglycemia in patients with type 2 diabetes caused a decrease in awakening response in the 4-8-h period following the event. These findings underscore the risks associated with nocturnal hypoglycemia because nocturnal hypoglycemia potentially affects the patient's ability to wake up and respond with an adequate intake of carbohydrates.