COPENHAGEN — Sleep apnea seems to have an immediate elevating effect on nighttime blood glucose levels in people with concomitant type 2 diabetes, said Dr. Maria Pallayova at the annual meeting of the European Association for the Study of Diabetes.
Previous data have shown the independent association between sleep-disordered breathing (SDB) and abnormal glucose metabolism. These findings provide a look at the immediate glycemic response to apneic episodes.
Medtronic/Minimed's continuous glucose monitoring system (CGMS) was used for several days in 30 patients with type 2 diabetes on diet or oral hypoglycemic therapy. Eight of the patients had severe SDB and a mean hemoglobin A1c level of 7.4%. The 22 who did not have SDB, had a mean HbA1c level of 6.5%. Those with SDB were referred to a sleep laboratory for overnight polysomnography, and the CGMS data were compared between the two groups, said Dr. Pallayova of PJ Safarik University, Kosice, Slovakia.
In the group without SDB, the CGMS revealed stable normoglycemia throughout the night. Those with severe untreated SDB had frequent episodes of sleep apnea/hypopnea (mean apnea-hypopnea index 57.64 episodes/hour) with severe oxygen desaturation (oxygen saturation 83%, minimal oxygen saturation 49%), followed by significant increases in blood glucose of up to 12.3 mmol/L (221 mg/dL).
The nocturnal increment in blood glucose was 1.11 mmol/L (19.98 mg/dL) in the SDB group, significantly greater than the 0.2 mmol/L (3.6 mg/dL) seen in the patients without SDB, and was strongly correlated with severe oxygen desaturation. The researchers found significant differences in both overall mean nocturnal glucose values—8.24 mmol/L (148.3 mg/dL) in the severe SDB group, compared with 6.15 mmol/L (110 mg/dL) in those without sleep apnea—and morning fasting glucose levels (8.01 vs. 6.6 mmol/L [144.2 vs. 118.8 mg/dL]).