THE EFFECT OF CONTINUOUS POSITIVE AIRWAY PRESSURE ON GLUCOSE EXCURSIONS IN DIABETICS WITH SLEEP-DISORDERED BREATHING: THE RESULTS OF CONTINUOUS GLUCOSE MONITORING

Sleep-disordered breathing (SDB) is often associated with impaired glucose metabolism. The study aimed at assessing immediate effect of CPAP on glucose excursions in type 2 diabetic patients with SDB measured with 72hour continuous glucose monitoring system (CGMS). 8 type 2 diabetic patients with SDB ( men, age 48,13 +/- 4,91 years, BMI 34,06 +/- 7,41 kg.m(- 2), HbA1c 7,3 +/- 1,4%) underwent 2 overnight polysomnographic examinations including diagnostic night and CPAP night. CGMS was applied on both occasions. Statistical analyses included paired Student's t-test. CPAP decreased apnoea- hypopnoea index (AHI) from 57,64 +/- 9,64.h(-1) to 8,05 +/- 4,42.h(-1) (p < 0,0001) with significant improvement of saturation. Frequent episodes of sleep apnoea/ hypopnoea and severe oxygen desaturation were followed by significant rise in blood glucose of up to 12,3 mmol.l(-1). Duration of post- hypoxic hyperglycemia was 50 +/- 10,79 min and its climax tended to be appeared up to 45min post-hypoxia. Nocturnal hyperglycemia strongly correlated with severe oxygen desaturation. Nocturnal glucose values were significantly higher during diagnostic night than during CPAP night ( 8,19 +/- 0,99 mmol.l(-1) versus 6,77 +/- 1,47 mmol.l(-1); p < 0,0001). CGMS also showed improved preprandial and 1,5-hour postprandial glucose levels for breakfast after CPAP night. The improvement in overall glucose levels was much greater in patients with BMI, 30 kg.m(-2) than in more obese patients. The results suggest that nocturnal hyperglycemia is closely related to desaturation and CPAP treatment may have an immediate decreasing effect on blood glucose in type 2 diabetic patients with SDB.