What is prediabetes, and what can you do about it?
Prediabetes means your blood sugar is higher than normal, but not yet in the diabetes range. In New Zealand, that's an HbA1c of 42–47 mmol/mol, under thresholds introduced on 1 July 2026. It's common, and it's a real opportunity: lifestyle change can cut the risk of developing type 2 diabetes by more than half, and many people return to normal blood sugar.
Being told your blood sugar is "a bit high" is easy to file away. You probably feel fine. But prediabetes isn't a waiting room. It's the stage where change has the most power, and the evidence for acting now is some of the strongest in medicine.
What is prediabetes?
Prediabetes means your average blood sugar has risen above normal, but not far enough to be diagnosed as type 2 diabetes. It's usually diagnosed with an HbA1c blood test, which shows your average blood sugar over about three months:
HbA1c result | What it means |
Below 42 mmol/mol | Normal range |
42–47 mmol/mol | Prediabetes |
48 mmol/mol or above | Type 2 diabetes range (a confirmatory test is usually needed between 48 and 52) |
Health New Zealand thresholds, effective 1 July 2026
A national survey found prediabetes in around one in four New Zealand adults, though it used older, international criteria (Coppell et al., NZMJ, 2013). It's more common in Māori and Pacific communities, and it usually has no obvious signs.
Has the prediabetes range changed in New Zealand?
Yes. On 1 July 2026, New Zealand aligned its HbA1c thresholds with World Health Organization standards. Prediabetes is now 42–47 mmol/mol (previously 41–49), and type 2 diabetes is 48 or above (previously 50). Around 200,000 people no longer meet the criteria for prediabetes, and around 34,500 more now meet the threshold for diabetes.
If your last HbA1c was 41, you're now in the normal range, but close to the line, so the habits below still matter.
If your last HbA1c was 48 or 49,you may now meet the criteria for type 2 diabetes. Talk to your doctor about a confirmatory test. Found early, type 2 diabetes can often be put into remission.
Why does the direction of your results matter?
Because blood sugar sits on a spectrum, not in boxes. The ranges are lines drawn across a continuous scale. When the lines moved in July, nobody's biology changed overnight: someone at 41 and someone at 42 have very similar risk.
Diabetes risk rises steadily across the HbA1c range (Zhang et al., Diabetes Care, 2010), and blood sugar usually drifts upwards for years before diabetes is diagnosed (Tabák et al., The Lancet, 2009). So your direction of travel often tells you more than any single result:
Rising year on year, even within the normal range, is worth acting on.
Steady or falling tells you your habits are working.
A trajectory isn't fixed. The changes below can flatten it, or turn it around. Ask for your previous HbA1c results so you can see your own.
Can prediabetes be reversed?
Often, yes. Many people bring their blood sugar back into the normal range, which researchers now call remission of prediabetes. In one study, people who returned to normal had a 73% lower risk of developing type 2 diabetes in the two years after the programme ended (Sandforth et al., Lancet Diabetes & Endocrinology, 2023).
The same research found that weight loss alone didn't guarantee it. Among people who lost at least 5% of their weight, those who returned to normal had bigger improvements in how their body responds to insulin, and less deep belly (visceral) fat. So where you lose weight from, and how well your body handles glucose, matter too. That's why activity matters as much as eating.
How much can lifestyle change reduce your risk?
By more than half, in some of the strongest evidence in preventive medicine:
Diabetes Prevention Program (US): lifestyle change reduced progression to type 2 diabetes by 58%, compared with 31% for a glucose-lowering medication. The goals were modest: about 7% weight loss and 150 minutes of activity a week.
Finnish Diabetes Prevention Study: the same 58% reduction (Tuomilehto et al., NEJM, 2001).
It lasts: at 21 years, the US lifestyle group still had a 24% lower rate of diabetes, and stayed diabetes-free for a median of 3.5 years longer.
In China's Da Qing study, a six-year lifestyle programme was followed for 30 years. Participants had 26% fewer deaths from any cause, 33% fewer cardiovascular deaths, and about 1.44 years of extra life expectancy (Gong et al., Lancet Diabetes & Endocrinology, 2019). These are group results, not predictions for any one person, but few health decisions are backed by evidence this strong.
What simple changes can you start today?
Small, steady steps add up. Here are practical places to start.
Weight and waist
Aim for 5–7% weight loss, around 5–6 kg for someone weighing 90 kg, and watch your waist, not just the scales.
Eating
Swap refined carbohydrates for whole grains, and cut back on sugary drinks and juice.
Rebalance your plate: half vegetables, a quarter protein, a quarter carbohydrate.
Movement
Aim for 150 minutes a week of brisk activity, the level used in the prevention trials.
Take a 10-minute walk after meals, and add some strength training. Muscle is one of the body’s biggest users of glucose.
Sleep and stress
Keep regular sleep times and notice your stress habits. Both affect the hormones that influence blood sugar.
If you've been prescribed medication for your blood sugar, keep taking it. These changes work alongside it.
What tests give a clearer picture of prediabetes?
HbA1c shows where your average blood sugar sits. Two tests show how hard your body is working to keep it there:
Fasting insulin. High insulin alongside near-normal glucose shows insulin resistance. Because insulin sensitivity is what most clearly separated people who returned to normal from those who didn't, it's a useful marker to track.
Continuous glucose monitoring (CGM). A small sensor on the upper arm shows how your meals, movement, sleep and stress affect your glucose, day and night, so changes can be targeted to you.
Neither test is part of a standard prediabetes check. In the Metabolic Clinic, both are included.
How does Autonomy approach prediabetes?
Knowing what to change is only half of it. Making changes last works best with a team. The American Heart Association notes that effective lifestyle programmes are usually delivered by dedicated multidisciplinary teams, and a 2019 analysis of 19 randomised trials found the greatest reductions in cardiovascular risk came from teams of three or more disciplines (van Namen et al., 2019).
That's how Autonomy's Metabolic Clinic works:
Doctors interpret your results, including fasting insulin and your glucose patterns, and build a plan around your own markers.
Registered nurses carry out your assessments and testing, and track your direction of travel.
Medically led health coaches turn the plan into everyday habits and help you keep them going.
We retest along the way, so you can see your trajectory change. With your consent, we report back to your referring doctor, and we work alongside any treatment you're already on.
Where to start
If you'd like to understand what your result means for you, start with a clinical Discovery Consultation with one of our doctors: 30 minutes, online or in person, $249, with no obligation. We'll look at your results and history, talk through what's driving your blood sugar, and explain what the programme would involve.
Dr Janani Krishnaswami (MD, MPH, DipABLM)
Clinical Director, Autonomy Health
Book a Discovery Consultation today.
References:
1. Health New Zealand | Te Whatu Ora. Notice of updated HbA1c diagnostic thresholds from 1 July 2026. See also Diabetes New Zealand, "Changes to HbA1c diagnostic criteria", 2026.
2. Coppell KJ, Mann JI, Williams SM, et al. Prevalence of diagnosed and undiagnosed diabetes and pre-diabetes in New Zealand: findings from the 2008/09 Adult Nutrition Survey. New Zealand Medical Journal 2013;126(1370):23–42.
3. Sandforth A, Jumpertz-von Schwartzenberg R, et al. Mechanisms of weight loss-induced remission in people with prediabetes: a post-hoc analysis of the randomised, controlled, multicentre Prediabetes Lifestyle Intervention Study (PLIS). Lancet Diabetes & Endocrinology 2023;11(11):798–810.
4. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. NEJM 2002;346:393–403.
5. Diabetes Prevention Program Research Group. 21-year follow-up. Diabetes Care 2025;48(7):1101.
6. Tuomilehto J, Lindström J, Eriksson JG, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. NEJM 2001;344:1343–1350.
7. Gong Q, Zhang P, Wang J, et al. Morbidity and mortality after lifestyle intervention for people with impaired glucose tolerance: 30-year results of the Da Qing Diabetes Prevention Outcome Study. Lancet Diabetes & Endocrinology 2019;7:452–461.
8. Zhang X, Gregg EW, Williamson DF, et al. A1C level and future risk of diabetes: a systematic review. Diabetes Care 2010;33(7):1665–1673. 9. Tabák AG, Jokela M, Akbaraly TN, et al. Trajectories of glycaemia, insulin sensitivity, and insulin secretion before diagnosis of type 2 diabetes: an analysis from the Whitehall II study. The Lancet 2009;373:2215–2221.
10. van Namen M, et al. Supporting lifestyle modification in patients with obesity or hypertension: a systematic review and meta-analysis of randomised trials. 2019.
