The growth in the sleep market is moving beyond the typical obstructive sleep apnea (OSA) patient. As research continues to explore sleep apnea and its comorbidities, new markets are emerging to provide near and long-term growth for HME and sleep providers. Two important markets right now are type 2 diabetes and cardiovascular disease (CVD).

Type 2 diabetes is certainly well recognized as a rampant global epidemic that everyone is talking about—from mainstream media to clinicians. It is a debilitating and often fatal disease characterized by disordered metabolism and abnormally high blood sugar, resulting from insufficient levels of the hormone insulin. The latest data from the National Institutes of Health (NIH) state that about 21 million people (or 8% of the US population) have type 2 diabetes. An astonishing 41 million people in the United States have pre-diabetes, which means the rates of type 2 diabetes have the potential to triple. If there is any doubt that this is a major health epidemic, consider the following facts:

• The average expenditure per person for patients with type 2 diabetes is $13,243 versus $2,560 for patients without diabetes.
• The prevalence in the United States has more than doubled in the last 10 years, with trends set to continue.
• The recent data show that approximately half of people with type 2 diabetes have OSA with an AHI of 10. The prevalence is higher in males (60%) than females (35%).

There is increasing evidence that OSA is associated with type 2 diabetes and with CVD. It is likely that more than half of people with type 2 diabetes suffer from some sort of sleep disturbance and that up to a third have OSA at a level where treatment would be recommended. Conversely, estimates suggest that up to 40% of people with OSA have diabetes.

CVD makes the connection important between SDB and diabetes. It has been well established that OSA is an independent risk factor for the development of hypertension and other CVD, including stroke and ischemic heart disease. But how does diabetes fit into this picture?

• Nearly 50% of diabetes patients are being treated for hypertension.
• Diabetes patients are two to three times more likely to have CVD (according to Diabetes Australia).
• People with type 2 diabetes are more than twice as likely to have a heart attack or stroke as people who do not have diabetes.
• CVD is the major cause of death in diabetes, accounting for some 50% of all diabetes fatalities, and much disability.

HOW ARE SDB AND DIABETES LINKED?

To understand the association between the disorders, it is important to comprehend a little of the physiology. During an obstructive apnea, a patient's oxygen levels start to drop. With decreasing levels of oxygen and an inability to breathe, the body panics—interpreting this as a life-threatening situation. There is an adrenaline rush, which stimulates the sympathetic nervous system and signals the body to wake up so that breathing can begin again. During this time, heart rate and blood pressure increase, and stimulation of glucose metabolism occurs. For someone with OSA, this can happen hundreds of time a night, resulting in overactivity of the sympathetic nervous system, and leading to increased blood pressure and a decrease in the body's ability to regulate glucose (blood sugar).

Ann Tisthammer

This decrease in glucose regulation is where diabetes factors in. The central factors in this mechanism are glucose, the main source of energy for the body, and insulin, a growth hormone made in the pancreas. The body metabolizes energy from foods containing carbohydrates. Through a process called "glucose metabolism," glucose is then transferred from the bloodstream into the body tissues/cells to allow the body to function. Insulin makes this transfer possible. Think of it as a "key" that opens the "door" to the red blood cells.

In a person with healthy glucose metabolism, food breaks down into sugars or glucose. The sugar (glucose) enters the blood, blood sugar levels rise, the body senses the sugar increase and sends a signal to the pancreas to make and release insulin into the bloodstream. This allows the sugar to pass from the bloodstream into the cells, providing energy. Normally, insulin unlocks the cell so sugar can pass from the bloodstream to the cell. In people with type 2 diabetes, the pancreas may not produce enough insulin, or the produced insulin cannot work properly. Using that key and door analogy, in type 2 diabetes the key does not work, or it is the wrong key to unlock the cell. This results in hyperglycemia—high glucose levels in the blood.

POSSIBLE MECHANISMS

While there is no one clearly identified cause of insulin resistance in OSA sufferers, there are several mechanisms.

• Increased sympathetic nervous activity resulting from repeated apneas may cause the release of glucose from the muscles into the bloodstream, resulting in residual circulating glycemia and hyperglycemia.
• Elevated levels of the hormone cortisol, released under conditions of stress in the body, lead to increased energy production and sympathetic activity causing excessive blood sugar levels and reduced insulin sensitivity.
• A sleep debt could be due to sleep fragmentation.
• Recurrent intermittent hypoxia leads to impairment in glucose homeostasis, leading to insulin resistance.

FUTURE DIABETES CARE WILL INCLUDE SLEEP

There is no doubt that the future of diabetes care will include sleep. A survey of 440 members of the American Diabetes Association (www.diabetes.org) showed that almost all (97%) believe OSA has a significant effect on the metabolic system. Most (89%) know that CPAP was the standard of treatment, and two-thirds (67%) know that CPAP improves insulin sensitivity. The majority (85%) believe the future of diabetes care will include assessment and treatment of OSA. This is great news because it means that these diabetes educators and clinicians have been educated about OSA.

The downside is that just over half (56%) are not routinely screening patients. This is where our focus must be, and thanks to the International Diabetes Federation (IDF), which recently released a consensus statement on sleep apnea and diabetes, the focus will be intensified.

IDF CONSENSUS

On June 7, 2008, the IDF published a consensus report highlighting the association between type 2 diabetes and sleep-disordered breathing (SDB). This consensus statement was presented at the American Diabetes Association meeting in June 2008, and published in Diabetes Research and Clinical Practice Journal. It is also available online at www.idf.org

The consensus report lists the following:

• SDB should be considered in the assessment of all patients with type 2 diabetes;
• the threshold for deciding if a patient should be assessed for SDB should be lower for patients with diabetes, because the positive impact of therapy on hypertension and quality of life has been established;
• CPAP is best for moderate to severe sleep apnea;
• people with sleep apnea should be routinely screened for diabetes; and
• health policy makers and the public should be made more aware of OSA and the significant financial and disability burden that it places on individuals and society.

EXPAND REFERRALS USING CLINICAL DATA

A critical element in expanding referrals is using the clinical data to support sales, marketing, and clinical efforts. Using peer-reviewed clinical research data will add to your credibility and greatly underscore the message you are conveying to your referring physicians and new call points. Listed below are some key studies that are instrumental in growing your referrals within the diabetes marketplace.

Controlling high blood pressure and the associated cardiac complications are top priorities for diabetes patients and educators. Recent clinical research has shown that treating OSA with positive airway pressure (PAP) therapy can reduce blood pressure, reduce after-meal blood glucose levels, and improve insulin sensitivity.

• Blood pressure: In a randomized, double-blind study by Becker et al,¹ there was an average 9.9 mm Hg reduction in blood pressure and normalization of AHI with therapeutic CPAP. An average reduction of 10 mm Hg in blood pressure corresponds to reduction in CVD risk by 37% and reduction in stroke risk by 56%.
• Blood glucose levels: Babu et al² followed 25 new OSA patients with T2DM (type 2 diabetes mellitus), measured before and after CPAP treatment, by a 72-hour continuous glucose monitor system. The results showed that postprandial (postmeal) glucose values significantly improved, and HbA1c (indicator of blood glucose levels) improved for those patients using CPAP more than 4 hours per day.
• Insulin sensitivity: Harsch et al studied 40 OSA patients without diabetes (five had abnormal glucose tolerance).³ The patients were put on CPAP after being diagnosed through a PSG. Insulin sensitivity improved after just 2 nights of CPAP therapy. The improvements were sustained after 3 months of therapy. Controlling insulin sensitivity, hence blood glucose, is the key goal for diabetes patients. Results may reflect decreasing sympathetic activity.

BUILDING YOUR SLEEP BUSINESS

It is important to know who the key players are when building your sleep business in any new marketplace. With the high prevalence of SDB and diabetes, along with the recent announcement by the IDF, the diabetes market is one that we cannot ignore. It also serves as a referral- and revenue-generating opportunity for your sleep program.

You might expect that endocrinologists are key players; however, they see mostly complex metabolic cases and type 1 diabetes patients. No more than 20% of people with type 2 diabetes ever see an endocrinologist. It is the primary care physician (PCP) who more often diagnoses and treats average type 2 diabetes patients. PCPs are the frontline physicians for hypertensive, obese, and diabetic patients (all strongly linked to SDB). The PCP should be one of your key call points here. Additionally, screening/diagnosing sleep apnea in these patients allows the PCP to retain patients in-house longer. The challenge is that PCPs are likely unaware of the association between diabetes and SDB, and rarely offer patient education on this topic.

Many diabetes patients are referred to a diabetes educator (DE) or certified diabetes educator (CDE) for lifestyle management. DEs are usually registered nurses and registered dietitians. The 15,000+ CDEs in the United States are responsible for promoting diabetes self-management by teaching patients to control exercise, diet, and glucose levels (and now sleep), and should be your key target. "No diabetes management tool—no new oral agent, insulin, or medical device—is as important as the services of a certified diabetes educator," says Christopher D. Saudek, MD, in a 2002 issue of Clinical Diabetes.⁴

The good news is that CDEs are ready to learn. They recognize that sleep apnea has a significant effect on the metabolic system, but according to the ADA survey, only about 20% are routinely assessing patients for SDB, and it is likely because 60% do not feel confident assessing patients for sleep apnea. This is a situation we can overcome.

Ask your diabetes educators to add simple screening questions to patient assessment forms. Questions include:

• Do you snore?
• Do you wake up tired after a full night sleep?
• Do you have high blood pressure?

Any patient who answers "yes" to one of these questions, go to the next step, which involves a Berlin Questionnaire. For patients who screen positively, refer them to a sleep physician or to their PCP for a referral to a sleep clinic.

BUILD YOUR BUSINESS

Build relationships with DEs in your area. Introduce the studies mentioned earlier, and then set up a time to present an overview of SDB. Invite the DEs, the physicians, and your sleep lab partners. You can become a strong resource by educating on the association between SDB and diabetes, and the IDF Consensus Statement. Next, set up a logistical meeting to discuss a screening protocol between the DEs and sleep lab partners. Educate both groups on the logistical flow, PSG process, screening process, and patient educational materials. This process will solidify a partnership that will drive sleep referrals, and your revenue, to the next level.

How do you find diabetes educators?

• Visit www.diabetes.org/education/eduprogram.asp for a list of ADA-approved education centers.
• Contact DEs in/near hospitals and physician clinics.
• Contact regional chapters of CDEs and offer educational presentations on sleep to their membership.
• Go through large hospitals to find the network of DEs and present at their biannual meetings.

Ann Tisthammer, RRT, is vice president, Clinical Education and Training (Americas), for ResMed Corp, Poway, Calif.

REFERENCES

1. Becker HF, Jerrentrup A, Ploch T, et al. Effect of nasal continuous positive airway pressure treatment on blood pressure in patients with obstructive sleep apnea. Circulation. 2003;107:68-73.
2. Babu AR, Herdegen J, Fogelfeld L, Shott S, Mazzone T. Type 2 diabetes, glycemic control, and continuous positive airway pressure in obstructive sleep apnea. Arch Intern Med. 2005;165:447-452.
3. Harsch IA, Schahin SP, Radespiel-Troger M, et al. Continuous positive airway pressure treatment rapidly improves insulin sensitivity in patients with obstructive sleep apnea syndrome. Am J Respir Crit Care Med. 2004;169:156-162.
4. Saudek CD. The role of primary care professionals in managing diabetes. Clinical Diabetes. 2002;20:65-66.