Why lack of sleep could increase your risk of type 2 diabetes

You probably know that sleeping badly makes you irritable and unable to focus the next day.

But here’s what you might not realise: when you regularly miss out on good sleep, it can seriously affect how your body processes food and burns energy.

Poor sleep can affect how your body regulates blood sugar and may put you at higher risk of developing type 2 diabetes, says Dr Devan Gounder, a specialist physician at Mediclinic Pietermaritzburg. However, sleep is often an overlooked factor when it comes to preventing diabetes.

“Lack of sleep can definitely increase your risk of developing type 2 diabetes mellitus,” he says. Most recently published studies have suggested that individuals with irregular sleep patterns have a 34% greater risk of developing this condition.”

The connection between sleep and blood sugar

Sleep is far more than a period of rest. While you sleep, your body performs a range of essential functions that help regulate hormones, repair tissues, and maintain healthy metabolism.

When sleep is disrupted or cut short, these processes are affected.

“Having irregular sleeping patterns or sleeping less than six hours a night stimulates your body to secrete higher levels of cortisol,” explains Dr Gounder. “Cortisol then stimulates your liver to release stored glucose and makes cells resistant to insulin.”

Insulin is the hormone responsible for helping glucose move from your bloodstream into your body’s cells, where it can be used for energy. When cells become resistant to insulin, blood sugar levels rise, increasing the risk of developing type 2 diabetes over time.

Can a few bad nights make a difference?

“While long-term sleep deprivation poses the greatest risk, even a short period of poor sleep can compromise your body’s glucose regulation,” says Dr Gounder. “It may affect blood sugar levels, as the sudden increase in cortisol can significantly reduce your body's ability to metabolise glucose.”

This means staying up late often, working night shifts, travelling across time zones, or going through periods of poor sleep can affect your metabolic health in measurable ways.

How much sleep do you need?

For most adults, the sweet spot appears to be 7-9 hours of undisturbed sleep at night. This helps the body use glucose more effectively and reduces the risk of type 2 diabetes, says Dr Gounder.

However, too much sleep is not necessarily better. “Sleeping more than nine hours is also associated with impaired glucose metabolism. A balanced sleep-wake cycle is most important for optimal metabolic health.”

When sleep disorders become part of the problem

Sleep problems are not always caused by going to bed too late.

Conditions such as heavy snoring, obstructive sleep apnoea, and frequent waking during the night can also place stress on your body and affect blood sugar regulation.

“People with disturbed sleep experience an increase in stress hormones such as cortisol and adrenaline as the body senses danger,” explains Dr Gounder. “This causes the liver to release glucose, leading to insulin resistance and ultimately type 2 diabetes.”

If you regularly wake up feeling unrefreshed despite spending enough time in bed, it may be worth discussing your symptoms with a healthcare professional.

Signs that poor sleep may be affecting your metabolism

Sleep deprivation doesn’t always show up as obvious exhaustion. Dr Gounder says warning signs that poor sleep may be disrupting metabolic health include:

• Frequent carbohydrate cravings
• Brain fog and difficulty concentrating
• Waking up feeling tired despite a full night’s sleep
• Feeling sleepy during daytime activities, such as meetings or watching television.

These symptoms may seem harmless at first, but over time they can indicate that your body's normal metabolic processes are being affected.

Small lifestyle changes to boost insulin resistance

Fortunately, insulin resistance can often improve with lifestyle changes. “Insulin resistance can be reversed if a person makes targeted lifestyle changes,” says Dr Gounder.

He recommends a combination of regular exercise, weight management, a lower-carbohydrate eating plan, and consistent, uninterrupted sleep.

To support better sleep and metabolic health:

• Aim for 7-9 hours of sleep each night
• Maintain a regular sleep schedule
• Choose higher-protein evening meals
• Avoid large meals close to bedtime
• Finish your evening meal at least two hours before going to sleep.

“Studies have confirmed that this strategy reduces insulin resistance and the risk of type 2 diabetes,” says Dr Gounder.

In a world that often treats sleep as optional, getting enough rest may be one of the most powerful things you can do for your long-term health.