Diabetes Mellitus Prevalence and Control in Sleep-Disordered Breathing

Epidemiological aspects of obstructive sleep apnea

Obstructive sleep apnea (OSA) is probably the most common respiratory disorder, with recent data from the United States and Europe suggesting that between 14% and 49% of middle-aged men have clinically significant OSA. The intimate relationship between OSA and obesity means that its prevalence will only increase as the global obesity epidemic evolves. At an individual level, OSA leads to a significant decrease in quality of life (QOL) and functional capacity, alongside a markedly increased risk of cardiovascular disease and death. Emerging data also suggest that the presence and severity of OSA and associated nocturnal hypoxemia are associated with an increased risk of diabetes and cancer. At a societal level, OSA not only leads to reduced economic productivity, but also constitutes a major treatable risk factor for hypertension, coronary artery disease (CAD) and stroke. This article addresses OSA from an epidemiological perspective, from prevalence studies to economic aspects to co-morbidity.

Association between obstructive sleep apnea severity and glucose control in patients with untreated versus treated diabetes

The purpose of this study was to determine whether the association between obstructive sleep apnea severity and glucose control differs between patients with newly diagnosed and untreated type 2 diabetes, and patients with known and treated type 2 diabetes. This multicentre cross-sectional study included 762 patients investigated by sleep recording for suspected obstructive sleep apnea, 497 of whom were previously diagnosed and treated for type 2 diabetes (treated diabetic patients), while 265 had no medical history of diabetes but had fasting blood glucose ≥126 mg dL(-1) and/or glycated haemoglobin (HbA1c ) ≥6.5% consistent with newly diagnosed type 2 diabetes (untreated diabetic patients). Multivariate regression analyses were performed to evaluate the independent association between HbA1c and obstructive sleep apnea severity in treated and untreated patients with diabetes. In untreated diabetic patients, HbA1c was positively associated with apnea-hypopnea index (P = 0.0007) and 3% oxygen desaturation index (P = 0.0016) after adjustment for age, gender, body mass index, alcohol habits, metabolic dyslipidaemia, hypertension, statin use and study site. The adjusted mean value of HbA1c increased from 6.68% in the lowest quartile of the apnea-hypopnea index (<17) to 7.20% in the highest quartile of the apnea-hypopnea index (>61; P = 0.033 for linear trend). In treated patients with diabetes, HbA1c was associated with non-sleep variables, including age, metabolic dyslipidaemia and insulin use, but not with obstructive sleep apnea severity. Obstructive sleep apnea may adversely affect glucose control in patients with newly diagnosed and untreated type 2 diabetes, but may have a limited impact in patients with overt type 2 diabetes receiving anti-diabetic medications.

Obstructive sleep apnea and diabetes mellitus

BACKGROUND

There is convincing evidence that obstructive sleep apnea (OSA) is highly associated with impaired glucose metabolism.

OBJECTIVES

Analyze the prevalence of OSA in type 1 and type 2 diabetes mellitus (DM) patients. Evaluate the influence of OSA on glycemic control.

METHODS

The adult patients with diabetes mellitus (DM) followed in the department of internal medicine were referred to our Sleep Unit. A home respiratory polygraphy was then performed on all patients with body mass index (BMI) <40 kg/m(2). The glycemic control was assessed by the value of glycated hemoglobin (Hba1c) in the previous 3 months.

RESULTS

A total of 46 patients were studied (20 men and 26 women), the mean age was 50±15 years and mean BMI was 28.6±4.9 kg/m(2). The mean Hba1c was 8.3±1.2. Twenty three patients had type 2 DM and 23 patients had type 1 DM. Twenty nine patients (63.0%) had OSA and 8.7% had severe OSA (AHI>30/h). The mean CT90 was 5.3±12.5 and the mean AHI was 13.6±18.3. The mean AHI was similar between type 1 and type 2 DM (15.7±24.5 Vs 11.6±8.9; p=0.46). The AHI was not correlated with the BMI. Type 2 DM patients with poor glycemic control (HbA1c>7.5%) had a significantly higher mean AHI (14.3±9.0 vs 6.4±6.2; p=0.038). This difference did not remain significant after adjustment for BMI (p=0.151).

CONCLUSIONS

The prevalence of OSA in type 1 DM is similar to that found in type 2 DM. We note the high prevalence of OSA in younger patients with type 1 DM.

Obstructive sleep apnoea, insulin resistance and adipocytokines

Obstructive sleep apnoea (OSA) is associated with multiple cardiometabolic abnormalities. Obesity is considered a major risk factor for the development of OSA, and it is also an established risk factor for insulin resistance and other cardiometabolic disorders. The enigma remains whether OSA has any causal role in the adverse metabolic profile, independent of or beyond that due to obesity. Sleep apnoeas and hypopnoeas result directly in intermittent hypoxaemia and cerebral arousals, both of which may evoke a cascade of downstream biologic responses in various body tissues and cells. Adipose tissue is a major source of adipocytokines many of which play important roles in the regulation of various metabolic functions. It is hypothesized that OSA may, through its unique pathophysiology, affect metabolic function through modulation of production or action of adipocytokines. This review focuses on insulin resistance, glucose metabolism and relevant adipocytokines in the context of OSA.

High-intensity statin therapy and regression of coronary atherosclerosis in patients with diabetes mellitus

Recommended low-density lipoprotein cholesterol (LDL-C) levels for patients with documented cardiovascular disease (CVD) are <100mg/dL (2.6mmol/l) with further reduction to <70mg/dL (1.8mmol/l) for higher-risk patients. High-intensity statin treatment may halt the progression as well as stabilize and induce regression of coronary atheromatous plaques while lowering CVD event rates. Diabetes mellitus (DM) is a major negative determinant of coronary artery plaque regression during statin therapy. However, regression of coronary atherosclerosis in DM patients is feasible to the same degree as in those without DM when very low LDL-C values (<70mg/dL; 1.8mmol/l) are achieved with high intensity statin treatment. The recent 2013 American College of Cardiology/American Heart Association (ACC/AHA) Guidelines on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults suggest to abandon specific LDL-C treatment targets. This strategy may deprive high risk patients, such as those with DM, from very high intensity statin treatment or drug combinations aiming to achieve very low LDL-C levels in order to reduce clinical events.

Obstructive sleep apnea as a risk factor for type 2 diabetes mellitus

Obstructive sleep apnea (OSA) is independently associated with cardiovascular and cardiometabolic risk in several large epidemiologic studies. OSA leads to several physiologic disturbances such as intermittent hypoxia, sleep fragmentation, and increase in autonomic tone. These disturbances have been associated with insulin resistance and type 2 diabetes mellitus (T2DM) in animal and human studies. Studies also suggest a bidirectional relationship between OSA and T2DM whereby T2DM itself might contribute to the features of OSA. Moreover, successful treatment of OSA may reduce these risks, although this is controversial. The purpose of this article is to review 1) the links and bidirectional associations between OSA and T2DM; 2) the pathogenic mechanisms that might link these two disease states; 3) the role of continuous positive airway pressure therapy in improving glucose tolerance, sensitivity, and resistance; and 4) the implications for clinical practice.