Miriam E Tucker

June 08, 2015

BOSTON — Obstructive sleep apnea (OSA) is common in people with type 1 diabetes and is associated with abnormal glycemia and microvascular complications but not body mass index (BMI), a new study finds.

The data were presented June 7, 2015 here at the American Diabetes Association (ADA) 2015 Scientific Sessions by Laurent Meyer, MD, an endocrinologist at Hopitaux Universitaires de Strasbourg, France.

The link between type 1 diabetes and OSA has been reported in three previous small trials, but this study of 90 adults with type 1 diabetes is the largest such trial to date and the first to use both continuous glucose monitoring and sleep studies to investigate the relationship between OSA and both hypo- and hyperglycemic variation, Dr Meyer explained.

In the study, OSA was particularly common among those with long disease duration and was associated with higher rates of diabetes complications, including retinopathy and peripheral neuropathy.

"The main message for clinicians is to think of OSA in type 1 patients with a long duration of diabetes. With the design of our study we can't say check at 10 or 15 years, but in my opinion if [a patient has] a duration of more than 20 years, it's important to check for OSA," Dr Meyer told Medscape Medical News in an interview.

Sleep apnea is ordinarily associated with obesity, but the French patients in this study were not excessively overweight, with a mean BMI of 26 kg/m2, suggesting that the OSA may be due to other factors.

"In our study the BMI was near normal.…I think perhaps it's linked to cardiac autonomic neuropathy.…Like other degenerative complications, it may be linked to an infiltration of soft tissue in the upper airways by glycated products. I think OSA must be considered a degenerative complication [of diabetes], like neuropathy or retinopathy," Dr Meyer said.

Asked to comment on the study, session chair Howard A Wolpert, MD, director of the Institute for Technology Translation at the Joslin Diabetes Center, Boston, Massachusetts, told Medscape Medical News, "I think it has fascinating implications. There's still a lot more work that needs to be done in terms of clarifying the issues, but if the association they found with peripheral neuropathy is related to the hypoxemia they're having and [since] there is a treatment for OSA [continuous positive airway pressure]…it would be really important to start treating people."

However, Dr Wolpert cautioned that the continuous glucose monitoring (CGM) part of the study was small, that it lasted only one night, that there were more smokers in the French study population than among US type 1 diabetes patients, and that no data were reported on activity patterns or insulin dosing.

"I think they need to do longer-term CGM analysis to actually see how representative these data are of the individual experience and the larger population," Dr. Wolpert said.

Dr Meyer agrees. "To be sure, it's important to have a long-term longitudinal study," he told Medscape Medical News.

OSA Found in 2 of 5 Type 1 Diabetes Patients

Obstructive sleep apnea, defined by an apnea/hypopnea index of greater than 10/hour, was diagnosed by either nocturnal polysomnography or by respiratory polygraphy in a total of 39 of the 90 patients (43%). Of those, 18 patients had severe OSA, defined as an index over 30/hour (20% of the total).

Compared with the 51 patients without OSA, those who had the condition were significantly older (mean age, 55 vs 48 years, P = .002) and had significantly longer diabetes duration (32 vs 24.5 years, P = .01).

But there were no significant differences between those who had OSA and those who didn't in terms of gender, BMI, total daily insulin dose, HbA1c, or, interestingly, by smoking status (35% of the total group were smokers; 17% of those with OSA smoked vs 15% of those who didn’t develop the condition).

Significantly more patients with OSA had diabetes-related complications, including micro- or macroalbuminuria (46% vs 16%, P = .03), retinopathy (95% vs 35%, P < .05), proliferative retinopathy (77% vs 2%, P < .05), peripheral neuropathy (54% vs 25%, P < .05), and acute coronary syndrome (33% vs 8%, P = .02).

Dr. Wolpert commented, "The association with retinopathy was very striking.…From the standpoint of causality, if these people were becoming hypoxemic at night related to this, it could be a big factor in why they developed the retinopathy. It ties into known mechanisms, but it's another factor."

OSA Correlates With Glycemic Variability

Continuous glucose monitoring for 24 hours was performed in 21 of the 90 patients. During the day, there were no differences in glycemic parameters between those with and without OSA.

During sleep, however, those with OSA spent significantly more time with hypoglycemic glucose values below 60 mg/dL (6.1% vs 2.3%, P < .05). They also trended toward more time spent with hyperglycemia, defined as glucose levels greater than 180 mg/dL (55% vs 32%), but this did not reach statistical significance.

Dr Meyer told Medscape Medical News that the mechanism for the association between OSA and glycemic excursions isn't clear but may have to do with hormones and/or cytokines. "Perhaps during these respiratory events you have modification of secretion that impacts metabolism. But we don't know precisely."

He acknowledged that the number of patients in the CGM part of the study was small, but "in a few months we'll have over 100 patients with simultaneous recording to see exactly the relationship between OSA and glucose fluctuations."

After that, he said, a next step would be to assess the effect of continuous positive airway pressure treatment on glucose fluctuations in type 1 diabetes patients with severe OSA.

Dr Meyer has no relevant financial relationships. Dr Wolpert is a consultant to Dexcom and Abbott Diabetes Care.

American Diabetes Association 2015 Scientific Sessions; June 7, 2015; Boston, MA. Abstract 177-OR

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