A New Treatment for Diabetes?
Abstract & Commentary
By Barbara A. Phillips, MD, MSPH, Professor of Medicine, University of Kentucky; Director, Sleep Disorders Center, Samaritan Hospital, Lexington, KY
Dr. Phillips serves on the speaker’s bureau of Cephalon, Boehringer Ingelheim, Merck, ResMed, and GlaxoSmithKline and is a consultant for Boehringer Ingelheim, Wyeth-Ayerst, and ResMed.
Synopsis: Patients who had both diabetes and sleep apnea had improved HbA1c and postprandial glucose when they used Continuous Positive Airway Pressure (CPAP) for more than 4 hours a night.
Source: Babu AR, et al. Type 2 diabetes, glycemic control, and continuous positive airway pressure in obstructive sleep apnea. Arch Intern Med. 2005;165:447-452.
Babu and colleagues recruited patients from a clinical population of stable type 2 diabetics who were referred for evaluation of sleep apnea. Twenty four patients completed the study and had adequate data for analysis. After diagnosis of sleep apnea and titration of CPAP, subjects completed baseline questionnaires, food diaries, histories and physical examinations, and baseline testing of glucose and HbA1c. This study was performed using continuous glucose monitoring for 72 hours at baseline and after 30-90 days of treatment with CPAP; the glucose monitoring system used was inserted subcutaneously, and sampled glucose every 5 minutes. CPAP compliance was assessed using measured time at pressure, and compliance was prospectively defined as use of CPAP for 4 or more hours per night. Neither weight nor diet changed over the follow-up period.
This population was fairly typical of patients encountered in sleep clinics. Their mean age was 50.7 years, mean Body Mass Index (BMI) was 42.7 kg/m2, mean duration of diabetes was about 8.3 years, mean baseline HbA1c was 8.3%, and most were men. They were sleepy, with a mean Epworth Sleepiness Score of 14, and had fairly severe sleep apnea, with an Apnea + Hypopnea Index (AHI) of 35 events per hour and a mean lowest oxygen saturation of about 77%. The average CPAP pressure was 12.4 cm H20. There were no significant differences between the compliant and noncompliant patients (besides hours of CPAP use).
Mean (of one hour) postprandial glucose measurements were significantly reduced after CPAP treatment for the whole group. For example, mean postprandial glucose after breakfast for the group fell from 191 mg/dL to 130 mg/dL (P < 0.05).There was also a statistically significant fall in the number of glucose values greater than 200 mg/dL for the whole study group after CPAP.
HbA1c levels fell from 8.3% to 7.9% for the whole group (P = 0.06), and from 9.2% to 8.6% for those who had baseline HbA1c levels of more than 7% (P = 0.02). There was a strong correlation between number of days of CPAP use and improvement (reduction) in HbA1c for those patients who were compliant with CPAP.
Commentary
Diabetes now affects more than 7% of Americans,1 and sleep apnea affects about 5%.2 Diabetes and sleep apnea frequently co-exist, since obesity is a risk factor common to both of them. The relationship between sleep-disordered breathing and diabetes has been recognized for decades,3 and both snoring and frank sleep apnea have been implicated in the development of glucose intolerance and/or insulin resistance.4,5 Several investigators have noted that sleep apnea is frequently seen in the Metabolic Syndrome (or Syndrome X), and Vgontzas et al argue convincingly that obstructive sleep apnea is part of the Metabolic Syndrome, describing a “bi-directional, feed forward, pernicious association between sleep apnea, sleepiness, inflammation, and insulin resistance, all promoting atherosclerosis and cardiovascular disease.”6
This study demonstrates that CPAP treatment can improve glucose control in diabetics, particularly poorly-controlled diabetics, just as it can improve blood pressure control in hypertensives,7,8 particularly poorly controlled hypertensives.9 It is worth looking for the sleep apnea in your patients with the Metabolic Syndrome, since CPAP can improve at least 2 of its components!
References
1. http://apps.nccd.cdc.gov/brfss/list.asp?cat=DB&yr=2004&qkey=1363&state=All. Accessed 8/19/05.
2. Young T, et al. Epidemiology of obstructive sleep apnea: a population health perspective. Am J Respir Crit Care Med. 2002; 165: 1217-1239.
3. Rees PJ, et al. Sleep apnoe`a in diabetic patients with autonomic neuropathy. J R Soc Med. 1981;74:192-195.
4. Al-Delaimy WK, et al. Snoring as a risk factor for type II diabetes mellitus: a prospective study. Am J Epidemiol. 2002;155:387-393.
5. Harsch I, et al. Continuous positive airway pressure treatment rapidly improves insulin sensitivity in patient with obstructive sleep apnea syndrome. Am J Respir Crit Care Med. 2004;169:156-162.
6. Vgontzas AN, et al. Sleep apnea is a manifestation of the metabolic syndrome. Sleep Med Rev. 2005;9: 211-224.
7. Pepperell JC, et al. Ambulatory blood pressure after therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnoea: a randomised parallel trial. Lancet. 2002;359:204-210.
8. Becker HF, et al. Effect of nasal continuous positive airway pressure treatment on blood pressure in patients with obstructive sleep apnea. Circulation. 2003;107:68-73.
9. Logan AG, et al. Refractory hypertension and sleep apnoea; effect of CPAP on blood pressure and baroreflex. Eur Respir J. 2003;21:241-247.
Patients who had both diabetes and sleep apnea had improved HbA1c and postprandial glucose when they used Continuous Positive Airway Pressure (CPAP) for more than 4 hours a night.
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