Diabetes and sleep are tightly linked, and the connection runs in both directions. Sleep apnea is a major risk factor for type 2 diabetes, and type 2 diabetes raises apnea severity. We have pulled together the figures from the Australian Institute of Health and Welfare (AIHW) and the Sleep Health Foundation, and here are the 15 numbers every Australian should know, along with what each one actually means for your nights.
A quick caution before the data. Statistics describe populations, not individuals. A figure like “around 40%” tells you how common an overlap is across many people; it cannot tell you whether you have a condition. Treat the numbers as a reason to ask questions, then take those questions to a GP.
Diabetes prevalence in Australia
- 1.7 million Australians have diabetes (~6.6% of the population, AIHW).
- Around 500,000 are estimated to have undiagnosed type 2.
- 1 in 4 Australian adults are at high risk of developing type 2 within 5 years.
The undiagnosed figure is the one to sit with. Type 2 diabetes can develop quietly, and many people feel little or nothing in the early stages. Tiredness, thirst and slow-healing cuts are easy to put down to a busy life, which is part of why so many cases sit unrecognised for a long time.
The high-risk figure matters for a different reason. It describes people who have not yet developed the condition but are heading that way, and that is exactly the group where changes to sleep, weight and activity can have the most effect. If you want the wider picture on weight, our obesity statistics for Australians piece covers how body weight and sleep feed into each other. For a broader view of how the country sleeps overall, see our Australian sleep statistics.
The sleep apnea overlap
- ~40% of people with type 2 diabetes also have moderate-to-severe obstructive sleep apnea.
- Conversely, ~30% of people with severe sleep apnea develop type 2 within 10 years if untreated.
- Type 2 diabetics with untreated apnea have significantly worse blood-glucose control.
Obstructive sleep apnea happens when the airway narrows or closes repeatedly during sleep, so breathing pauses and the brain briefly wakes the body to restart it. Most people do not remember these micro-awakenings. They just feel unrefreshed in the morning, or they are told by a partner that they snore, snort or stop breathing for a few seconds at a time. There is a good Wikipedia overview of obstructive sleep apnea if you want the terminology explained.
The two-way overlap in these figures is the point. If a large share of people with type 2 diabetes also have significant apnea, and a meaningful share of people with severe apnea go on to develop type 2, then the two conditions should not be thought of in separate boxes. Our own sleep apnea statistics for Australia go deeper on the breathing side of the story.
The third bullet is the practical one. Blood-glucose control is hard enough with the right medication, diet and activity. Add nightly oxygen dips and fragmented sleep, and the body is working against itself. People managing diabetes who never feel rested are worth a second look for undiagnosed apnea.
Sleep duration and diabetes risk
- Sleeping under 6 hours raises diabetes risk by ~30% even controlling for weight and activity.
- Sleeping over 9 hours regularly is also associated with elevated risk (the curve is U-shaped).
- Shift workers with disrupted circadian rhythm have ~40% higher type 2 incidence.
A U-shaped curve means risk is lowest in the middle and rises at both ends. Short sleep is the easier end to understand: a tired body handles glucose less well and tends to crave energy-dense food. Long sleep is trickier. It may be a marker of something else going on, such as poor-quality sleep that needs extra hours to compensate, or an underlying health condition, rather than a cause in itself. The statistic says “associated with”, and we keep that hedge deliberately.
The shift-work figure shows why timing matters as well as quantity. Your body runs on an internal clock, and meals, light and sleep that fall out of step with it appear to put pressure on blood sugar regulation. If you work nights, consistency within your own pattern is worth more than a perfect schedule that you cannot keep.
What diabetes costs Australia
- Diabetes costs the Australian healthcare system ~$4 billion directly each year.
- Indirect costs (lost productivity, complications) push the total over $14 billion.
- Untreated sleep apnea adds an estimated $1.4 billion in additional diabetes-related costs annually.
Direct costs are the visible bills: medication, hospital care, appointments and testing. Indirect costs are the ones people rarely see, including days off work, reduced capacity at work and the long-term complications that come with poorly controlled blood sugar. The gap between the two figures is a reminder that most of the burden lands outside the clinic.
The apnea line is the one we find most interesting. It suggests that a share of diabetes-related cost is tied to a sleep problem that can be identified and treated. I’d argue that makes sleep testing one of the better-value conversations in this area, and one that is talked about far less than diet or exercise.
How diabetes and sleep affect each other
Apnea fragments sleep, raises overnight cortisol, and shifts insulin sensitivity. Insulin resistance, in turn, contributes to weight gain and reduced muscle tone in the upper airway, which worsens apnea. The loop is biological, not psychological.
Take each step slowly. Broken sleep puts the body in a mild stress state, and cortisol is one of the hormones that pushes blood glucose up. Over time the cells respond less well to insulin. Weight tends to creep up, and extra tissue around the neck and throat, together with weaker muscle tone in the airway, makes it easier for the airway to collapse during sleep. More collapse means more fragmented sleep, and the cycle repeats.
The phrase “not psychological” matters. People caught in this loop are sometimes told, or tell themselves, that they just need more willpower. That misses the mechanism. Breaking the loop usually means treating one of the links directly, which is why the next section is built around practical steps rather than resolve.
What you can actually do
- If you snore loudly, wake gasping, or wake unrested most days, ask a GP about a sleep study. Apnea is one of the most under-diagnosed conditions in Australia (~80% of moderate-to-severe cases unknown).
- Treating apnea (CPAP, mandibular advancement device, weight loss) improves HbA1c by an average of 0.4 percentage points — clinically meaningful.
- Consistent sleep schedule and 7–9 hours nightly reduce diabetes risk regardless of weight changes.
- A supportive mattress matters because broken sleep from a sagging mattress fragments sleep similarly to apnea (less severely). See how to recognise a bad mattress.
HbA1c is a blood test that reflects average blood glucose over recent weeks, so it is a useful yardstick for whether a change is helping. Your GP or diabetes care team will explain what your own result means. Do not adjust any treatment on the basis of an article; talk to them first.
On the sleep study itself, our view is that it is the cheapest, highest-leverage step in the chain, and most GPs will refer for one if asked. The common mistake is waiting for symptoms to become severe. Many people with apnea assume that snoring is just snoring, or that being tired is normal at their age, and so never raise it.
The mattress point deserves proportion. A sagging or unsupportive mattress is not a substitute for treating apnea, and it will not cause diabetes. What it can do is add its own layer of broken sleep, which is unhelpful when you are already trying to protect your rest. If you are not sure whether yours is past its best, the warning signs are easy to check.
What this means for sleep buyers
If you’re managing type 2 diabetes (or a partner has it), the sleep environment matters more than for the average household. Adjustable beds (head-up sleeping reduces apnea events), cool bedding (heat aggravates apnea), and a mattress that doesn’t make repositioning hard are all useful. See our guide on adjustable beds.
A few practical checks when you are shopping. Ask how easily you can change position on a given mattress, because a surface that grips or sinks can make turning over a chore, and that disturbs sleep for both of you. Think about heat: bedding that traps warmth tends to wake people, and the original point about heat aggravating apnea gives you another reason to favour breathable fabrics. And if an adjustable base is on your list, check that raising the head end is comfortable for the whole night rather than just for a quick test in a showroom.
Be sceptical of any product that promises to fix apnea or diabetes. A bed, a pillow or a set of sheets can support better sleep conditions, but none of them replaces medical assessment or treatment. If you are weighing up what to spend, keep the money for the things that carry the evidence: a sleep study if you need one, then the bedding that makes the treatment easier to stick with.
Trusted sources to read next
These are the organisations behind much of the data above, and they are the right places to go for medical detail rather than relying on a summary like this one. External references: Sleep Health Foundation, Australian Institute of Health and Welfare, Diabetes Australia.
If you are curious about the condition itself, Wikipedia’s entry on type 2 diabetes is a reasonable plain-language starting point. For anything about your own health, see your GP.
