- Age, family history and ethnicity raise your risk of prediabetes, but you cannot change them.
- The biggest changeable risk factors are extra weight around the waist, inactivity, diet quality, sleep, smoking and alcohol.
- In one large study, about 9 in 10 cases of type 2 diabetes were linked to lifestyle factors.
- You do not need to fix everything. Improving one or two habits already lowers risk.
Prediabetes rarely has a single cause. It usually builds up from a mix of things you are born with and things you do every day. The factors you inherit load the dice; your daily habits decide how often they roll against you. The encouraging message from decades of research is that the everyday factors matter a lot, and they respond to small changes.
What you can and cannot change
- Age: risk rises after 35–40
- A parent or sibling with type 2 diabetes
- South Asian, Black, Hispanic/Latino, Native American or Pacific Islander heritage
- A history of gestational diabetes or a baby over 4 kg (9 lb)
- Polycystic ovary syndrome
- Weight, especially around the waist
- How much you move and how long you sit
- What you eat and drink
- Sleep quantity and quality
- Smoking and heavy drinking
- Chronic stress
If you have several of the fixed risk factors, the changeable ones become even more important. They are where your effort pays off.
How much lifestyle matters
Hu et al., NEJM 2001 (Nurses’ Health Study); Aune et al., Eur J Epidemiol 2015 and 2013.
Risk factors also add up. In the Nurses’ Health Study, women who kept a healthy weight, exercised for at least half an hour a day, ate a high-fiber diet low in refined carbs, did not smoke and drank little alcohol had about 90% fewer cases of diabetes than everyone else. Each extra healthy habit lowered risk further. The same pattern appears in men and in studies from Asia and Europe: every step in the right direction counts, even if you never reach all five.
The six changeable risk factors
Fat around the waist and in the liver is the strongest driver of insulin resistance. It matters more than your weight on the scale.
Muscles are your main glucose store. When they are idle, sugar stays in the blood. Long sitting adds risk even if you exercise.
Diets high in refined grains, processed meat and sugary drinks raise risk; fiber, whole grains, legumes and vegetables lower it.
Regularly sleeping under 6 hours, or having untreated sleep apnea, makes the body more insulin resistant.
Smoking raises diabetes risk by about a third. Heavy drinking adds calories and liver fat.
Long-term stress hormones raise blood sugar and make it harder to sleep, eat well and stay active.
Check your waist, not just your weight
Measure around your waist, halfway between your lowest rib and the top of your hip bone, and divide by your height. A result of 0.5 or more suggests extra fat around the organs.
Waist-to-height ratio
Works in centimetres or inches. People of Asian heritage often carry more organ fat at a lower weight.
Quick self-check
Tick the statements that apply to you most weeks. Each tick is a place where a small change can lower your risk.
- I do less than 150 minutes of brisk walking or similar activity a week.
- I often sit for more than 2 hours without a break.
- I have a sugary drink or fruit juice most days.
- White bread, white rice or pastries make up most of my carbs.
- I eat fewer than 3 servings of vegetables a day.
- I usually sleep less than 6 hours, or I snore loudly.
- I smoke, or often have more than 2 alcoholic drinks a day.
Want a score? Our Diabetes Risk Check combines your age, family history, waist, activity and blood pressure in about a minute.
Small changes, big effect
You do not need a complete overhaul. In prevention trials, people who changed just a few habits, such as walking daily, cutting sugary drinks and eating more fiber, lowered their risk substantially. Pick the ticks above that feel easiest to change and start there. Treating Prediabetes explains the changes that matter most.
MythIf diabetes runs in my family, there is nothing I can do.
FactGenes raise risk, but lifestyle changes lower it just as much in people with a family history.
Common questions
Which risk factor matters most?
For most people, extra fat around the waist and low physical activity have the biggest effect, and they are closely linked. Improving one usually helps the other.
Does eating sugar cause prediabetes?
Sugar alone does not cause it, but sugary drinks in particular are linked with higher risk because they add a lot of fast sugar and calories without filling you up.
How quickly does risk go down after I change?
Some benefits start within days: muscles become more sensitive to insulin after each walk or workout. Blood sugar tests such as HbA1c usually improve within about 3 months of consistent changes.
I am slim. Can I still be at risk?
Yes. Family history, age, ethnicity, inactivity, sleep and smoking all matter regardless of weight. A blood test is the only way to know.
Already diagnosed with type 2 diabetes? Read Type 2 Diabetes Risk Factors: What You Can and Can’t Change in our 18-part Type 2 Diabetes Basics series.
- Age, genes and ethnicity load the dice; daily habits decide much of the outcome.
- Waist size, activity, diet quality, sleep, smoking and stress are the main changeable factors.
- A waist-to-height ratio of 0.5 or more is a useful warning sign.
- Start with the one or two changes that feel easiest.
- Next: Signs and symptoms of prediabetes.
Sources
- Hu FB, Manson JE, Stampfer MJ, et al. Diet, lifestyle, and the risk of type 2 diabetes mellitus in women. N Engl J Med. 2001;345(11):790–797.
- Aune D, Norat T, Leitzmann M, Tonstad S, Vatten LJ. Physical activity and the risk of type 2 diabetes: a systematic review and dose–response meta-analysis. Eur J Epidemiol. 2015;30(7):529–542.
- Aune D, Norat T, Romundstad P, Vatten LJ. Whole grain and refined grain consumption and the risk of type 2 diabetes: a systematic review and dose–response meta-analysis of cohort studies. Eur J Epidemiol. 2013;28(11):845–858.
- Pan A, Wang Y, Talaei M, Hu FB, Wu T. Relation of active, passive, and quitting smoking with incident type 2 diabetes: a systematic review and meta-analysis. Lancet Diabetes Endocrinol. 2015;3(12):958–967.
- Cappuccio FP, D’Elia L, Strazzullo P, Miller MA. Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis. Diabetes Care. 2010;33(2):414–420.
- Ashwell M, Gunn P, Gibson S. Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors. Obes Rev. 2012;13(3):275–286.
This article is for general education and is not a substitute for advice from your own doctor or healthcare team.