Introduction

Do you wake up feeling tired despite a full night’s sleep, or have you been told about your loud snoring? Then, you might be experiencing sleep apnoea. This condition is characterised by frequent interruptions in breathing during sleep.

Sleep apnoea is linked to multiple health hazards, one of these hazards is diabetes mellitus (DM). People with type 2 diabetes are more likely to have sleep apnea, and vice versa.

Diabetes mellitus is the most prevalent endocrine condition that affects about 100 million individuals globally (6% of the population). It occurs through the pancreas' inability or lack of ability to produce enough insulin, which causes variations in blood glucose levels.¹

In this article, we will provide a comprehensive discussion on the relation between sleep apnoea and diabetes mellitus and the optimal management options.

Symptoms of sleep apnoea

There is a wide range of symptoms, but the most common are:²

• Snoring loudly
• Often stopping breathing when you're asleep
• Gasping and choking when you sleep
• Sweating when you wake up at night
• Not feeling rested in the morning after a sleepless night
• Headaches in the morning
• Drowsiness during the day
• Fatigue
• Gaining weight quickly
• Impairments in cognition
• Depression

How does sleep apnea affect blood glucose levels?

Sleep apnoea comes in two forms, which are:

Obstructive Sleep Apnoea(OSA)

When your upper airway repeatedly becomes clogged while you sleep, it might reduce or stop airflow entirely.  It is the most prevalent kind of sleep apnoea. Obesity, enlarged tonsils, or hormonal fluctuations are just a few factors that might make it more likely that you will develop obstructive sleep apnoea.

Central Sleep Apnoea

When your brain fails to deliver the necessary signals for breathing, it might result in central sleep apnoea.  It can be brought on by illnesses that alter the way your brain communicates with your chest, and airway muscles.

The obstructive sleep apnoea is most closely linked to the onset of type 2 diabetes. One of the most concerning ways in which diabetes is affected by sleep apnea involves blood glucose.^3,4 

Impaired glucose tolerance and insulin sensitivity

OSA is characterised by repeated blockages of the upper airways during sleep, leading to intermittent drops in oxygen levels and frequent awakenings. It causes insulin resistance because of poor glucose metabolism in the liver, muscle, and pancreas.⁴

Insulin resistance

Sympathetic nervous system (SNS) activation

In OSA, there is increased SNS activity during wakefulness and sleep. Increased SNS activity will increase the circulating catecholamines, which increase glucose production, impair insulin secretion, and participate in causing insulin resistance.⁴

Effect of intermittent hypoxia (IH) on adipose tissue

IH is an intermittent lack of oxygen, which induces dyslipidemia and modifies the function of adipose tissue, resulting in an enhanced release of free fatty acid. Free fatty acids increase insulin resistance in the liver, muscle, and adipose tissues via several pro-inflammatory mechanisms and by decreasing insulin-sensitising hormones like adiponectin.⁴

Pancreatic endocrine dysfunction

IH can cause dysfunction of pancreatic beta cells in patients with OSA, including beta-cell death, decreased insulin content, and impaired insulin production. These effects are most likely mediated by oxidative stress and inflammation within the pancreas that contributes to overall pancreatic endocrine dysfunction.⁴

Challenges in diabetes management

Several challenges in diabetes management occur due to the co-occurrence of sleep apnea, which include: 

Poor glycemic control

The key to the management of diabetes is good glycemic control, which simply means maintaining blood sugar levels within the target range. The stress and insulin resistance caused by sleep disorders make it hard to maintain this level.²

The activation of SNS, systemic inflammation, oxidative stress, and hormonal imbalances can all go in the direction of insulin resistance, and blood sugar intolerance, and finally lead to type 2 diabetes.⁵

Poor glycemic control is associated with an increased risk for complications like heart disease, nerve damage, and vision problems.²

Increased risk of diabetes complications

Diabetes and sleep apnoea together greatly raise the risk of chronic health problems, such as kidney disease, nerve damage, and cardiovascular disease. The shortness of sleep and sleep interruption linked to sleep apnoea may worsen glucose metabolism even more, raising the risk of cardiovascular events, which is a leading cause of death in individuals with diabetes.²

Type 2 diabetes can exacerbate OSA through mechanisms such as peripheral neuropathy, impaired microvascular regulation, and increased oxidative stress. It may also involve alterations in central respiratory control related to diabetes, although the exact mechanism is not clearly understood yet.⁵

To reduce this compounded risk a more integrated strategy for the care of these two disorders is necessary.²

Interference with diabetes medication

This indicates that if sleep apnoea is left untreated, diabetes may be harder to manage with medication alone and may need frequent dosage adjustments. Certain drugs, which are often used to treat diabetes, might cause weight gain. This exacerbates sleep apnoea and makes treatment more difficult for both conditions.²

Role of sleep apnoea treatment in diabetes management

Effect of CPAP (continuous positive airway pressure) therapy on glycemic control

CPAP mechanised treatment for sleep-disordered breathing prevents the collapse of the airway during sleep. It is associated with the following:⁵

• Improvement in sleep quality
• Reduction in excessive daytime sleepiness
• Enhanced quality of life
• A decrease in blood pressure

CPAP therapy lowers SNS activity. Thus, it minimises the risk of glycogenolysis (the stored carbohydrate is broken down into glucose to provide immediate energy), gluconeogenesis (formation of glucose and other carbohydrates), reduced insulin release, and increased lipolysis(the breakdown of triglycerides into free fatty acids within cells).⁵

It also lowered the secretion of stress-related hormones, like cortisol and catecholamines, associated with insulin resistance and hyperglycemia. It significantly reduces HbA1c, which is a marker of long-term blood glucose levels.⁵⁽⁷⁾

Impact of weight loss and lifestyle modifications

OSA and type 2 diabetes mellitus share a common cause: obesity. Obesity, on the other hand, significantly increases the risk to both. Weight loss is an essential factor in the management of obese people with OSA and diabetes mellitus. Reducing fat deposition at the neck, which causes narrowing of the airways when sleeping, and at the belly, which reduces abdominal fat and so increases lung capacity, helps to alleviate OSA symptoms.⁶

Effective weight loss by lifestyle treatments, including food and exercise, improves insulin sensitivity and helps to improve glucose levels in diabetes mellitus patients with OSA. A healthy lifestyle, which includes food adjustments and increased physical exercise, is very important in overcoming obesity. Control of obesity helps in the management of both DM and OSA. Also, it aids in reducing inflammation and oxidative stress indicators linked to the beginning of the development of both disorders.⁶

Summary

Sleep apnoea and diabetes are closely associated medical diseases that have a major impact on one another. If you have diabetes, you should be aware of the risk of sleep apnoea and seek treatment if you have symptoms like loud snoring, daytime weariness, or difficulties sleeping. Similarly, if you have sleep apnoea, you should understand how it affects your blood sugar levels to manage your diabetes.

If sleep apnoea is treated and lifestyle adjustments are done, it will assist in maintaining blood sugar levels stable, and lower the risk of complications, from both disorders. An integrated strategy can help you maintain your health and improve your quality of life.

If you think you might have sleep apnoea, or if you are having a hard time controlling your diabetes, talk to your healthcare provider. In many cases, early diagnosis and treatment can drastically improve your overall health.

FAQs

What are the lifestyle changes for sleep apnoea?

These include engaging in regular physical activity, keeping good sleeping patterns and body weight, limiting alcohol and caffeine use, and quitting smoking.

Is there a connection between sleep apnoea and diabetes?

Yes, sleep apnoea and diabetes are strongly associated with one another.

What does untreated sleep apnea lead to?

Sleep apnoea has been linked with other diseases, such as type 2 diabetes, strokes, and heart attacks, and even reduced one's lifespan.