Sleep Apnea Associated With Hyperglycemia in Diabetes

COPENHAGEN — Sleep apnea appears to have an immediate elevating effect on nighttime blood glucose levels in people with concomitant type 2 diabetes, Dr. Maria Pallayova said at the annual meeting of the European Association for the Study of Diabetes.

Previous studies have documented the independent association between sleep-disordered breathing (SDB) and abnormal glucose metabolism. However, the findings of this study, which used continuous glucose monitoring, provide a closer 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 A_1c level of 7.4%. The other 22, who did not have SDB, had a mean HbA_1c 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 the Pavol Jozef Safarik University, Kosice, Slovakia.

In the group without SDB, the CGMS revealed stable normoglycemia throughout the night. In contrast, 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 82.5%, minimal oxygen saturation 49.13%), 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 value of 0.2 mmol/L (3.6 mg/dL) seen in the patients without SDB, and was strongly correlated with severe oxygen desaturation. The peak of apnea-induced hyperglycemia tended to occur within 1 hour of severe oxygen desaturation, and the hyperglycemia lasted for a mean of 48 minutes post hypoxia before returning to normal, Dr. Pallayova noted.

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]).

However, there were no significant differences between the groups in daytime CGMS glucose levels, and no associations were seen between arousal frequency and nocturnal hyperglycemia, she reported.

“Obstructive sleep apnea is not only obstruction; it is a cardiovascular and metabolic nightmare,” Dr. Pallayova said.

“We have to be aware of the fact that untreated sleep apnea may adversely influence glucose control and contribute to the development of late diabetes complications,” she added. “Both sleep-disordered breathing and diabetes mellitus are common, serious, treatable, and underdiagnosed, and they require a high index of suspicion.”

COPENHAGEN — Sleep apnea appears to have an immediate elevating effect on nighttime blood glucose levels in people with concomitant type 2 diabetes, Dr. Maria Pallayova said at the annual meeting of the European Association for the Study of Diabetes.

Previous studies have documented the independent association between sleep-disordered breathing (SDB) and abnormal glucose metabolism. However, the findings of this study, which used continuous glucose monitoring, provide a closer 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 A_1c level of 7.4%. The other 22, who did not have SDB, had a mean HbA_1c 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 the Pavol Jozef Safarik University, Kosice, Slovakia.

In the group without SDB, the CGMS revealed stable normoglycemia throughout the night. In contrast, 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 82.5%, minimal oxygen saturation 49.13%), 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 value of 0.2 mmol/L (3.6 mg/dL) seen in the patients without SDB, and was strongly correlated with severe oxygen desaturation. The peak of apnea-induced hyperglycemia tended to occur within 1 hour of severe oxygen desaturation, and the hyperglycemia lasted for a mean of 48 minutes post hypoxia before returning to normal, Dr. Pallayova noted.

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]).

However, there were no significant differences between the groups in daytime CGMS glucose levels, and no associations were seen between arousal frequency and nocturnal hyperglycemia, she reported.

“Obstructive sleep apnea is not only obstruction; it is a cardiovascular and metabolic nightmare,” Dr. Pallayova said.

“We have to be aware of the fact that untreated sleep apnea may adversely influence glucose control and contribute to the development of late diabetes complications,” she added. “Both sleep-disordered breathing and diabetes mellitus are common, serious, treatable, and underdiagnosed, and they require a high index of suspicion.”

COPENHAGEN — Sleep apnea appears to have an immediate elevating effect on nighttime blood glucose levels in people with concomitant type 2 diabetes, Dr. Maria Pallayova said at the annual meeting of the European Association for the Study of Diabetes.

Previous studies have documented the independent association between sleep-disordered breathing (SDB) and abnormal glucose metabolism. However, the findings of this study, which used continuous glucose monitoring, provide a closer 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 A_1c level of 7.4%. The other 22, who did not have SDB, had a mean HbA_1c 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 the Pavol Jozef Safarik University, Kosice, Slovakia.

In the group without SDB, the CGMS revealed stable normoglycemia throughout the night. In contrast, 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 82.5%, minimal oxygen saturation 49.13%), 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 value of 0.2 mmol/L (3.6 mg/dL) seen in the patients without SDB, and was strongly correlated with severe oxygen desaturation. The peak of apnea-induced hyperglycemia tended to occur within 1 hour of severe oxygen desaturation, and the hyperglycemia lasted for a mean of 48 minutes post hypoxia before returning to normal, Dr. Pallayova noted.

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]).

However, there were no significant differences between the groups in daytime CGMS glucose levels, and no associations were seen between arousal frequency and nocturnal hyperglycemia, she reported.

“Obstructive sleep apnea is not only obstruction; it is a cardiovascular and metabolic nightmare,” Dr. Pallayova said.

“We have to be aware of the fact that untreated sleep apnea may adversely influence glucose control and contribute to the development of late diabetes complications,” she added. “Both sleep-disordered breathing and diabetes mellitus are common, serious, treatable, and underdiagnosed, and they require a high index of suspicion.”