Why type 2 diabetes is rising fastest in under-40s, not older adults

The shift nobody expected: type 2 diabetes under 40 in the UK

Type 2 diabetes has long been thought of as a condition of later life. That picture is out of date. In the UK, diagnoses of type 2 diabetes under 40 have been climbing consistently faster than in any older age group for the best part of a decade, and the gap is widening, not narrowing.

Diabetes UK’s analysis of NHS data found that cases in under-40s rose by around 40% between 2016/17 and 2022/23, compared with 25% in over-40s, taking the number of under-40s living with type 2 diabetes to nearly 168,000. A more recent Diabetes UK review of 2017/18–2023/24 data found the trend has accelerated further and is especially steep in women: diagnoses in women under 40 rose 47%, more than double the 22% increase among women aged 40 to 79, while men under 40 saw a 34% rise over the same period. NHS Digital’s National Diabetes Audit separately puts the number of under-40s with type 2 diabetes at 164,360 for 2023/24.

This isn’t a UK-only pattern. Imperial College London researchers reported in 2026 that incidence is rising fastest in the young across England and Wales, and that it’s now broadening into groups previously seen as lower-risk — including white populations, not only the Black and South Asian communities historically most affected. Globally, incidence in 10 to 24-year-olds rose by around 120% between 1990 and 2021.

What’s actually driving it — and why it isn’t just “eating too much”

It’s tempting to reach for a simple explanation: young people are eating more and moving less. There’s truth in that, but it understates what’s really going on, and framing it purely as individual choice misses evidence pointing to a shared, structural driver.

Diet quality has shifted substantially. A 2024 study in The Lancet Regional Health – Europe, following over 311,000 people across eight countries, found each 10% increase in ultra-processed food intake was linked to a 17% higher risk of developing type 2 diabetes — savoury snacks, processed meat products, ready meals and sugar-sweetened drinks carried the strongest associations. Separate research published in Diabetes Care found this risk held even after accounting for body weight and overall diet quality, suggesting something about how these foods are made and consumed — not just their calorie content — matters.

Inactivity compounds this. Daily life for many people under 40 now involves far less incidental movement — desk-based work, commuting by car, screen-based leisure — than a generation ago, and inactivity independently worsens insulin resistance.

Then there’s deprivation. Diabetes UK’s data shows children in the most deprived parts of the UK are around five times more likely to develop type 2 diabetes than those in the least deprived areas. Cheaper, more accessible food tends to be more processed; safe spaces to exercise, time to cook, and the general “bandwidth” for prevention are all harder to come by under financial pressure. None of this excuses inaction, but it does mean the rise reflects environment and inequality as much as personal decisions — a distinction that matters when working out where solutions need to focus.

Why type 2 diabetes diagnosed young tends to hit harder

One of the more sobering findings from research into youth-onset type 2 diabetes is that it isn’t simply “the same disease, just earlier.” The long-running US TODAY study, which has followed young people with type 2 diabetes for over 15 years, found the condition tends to progress faster in younger patients, with quicker decline in the insulin-producing cells of the pancreas than typically seen when the disease develops later in life.

The follow-up TODAY2 study found that within 15 years of diagnosis, roughly 60% of participants had developed at least one diabetes-related complication, and nearly a third had two or more — including early signs of kidney disease in around half of participants and retinopathy (eye damage) in close to half. Neuropathy, nerve damage causing numbness, tingling or pain, was found in the large majority.

The likely explanation is exposure time combined with biology: a diagnosis at 28 rather than 58 means three decades more of elevated blood sugar acting on blood vessels, nerves and organs, and some evidence suggests the underlying insulin resistance itself may behave more aggressively at younger ages. This is exactly why catching risk early, rather than waiting for a diagnosis to arrive, matters more the younger you are.

What this means if you’re in your 20s or 30s

None of this is a reason to panic, but it is a reason to take risk seriously rather than assuming diabetes is “an old person’s problem.” A few practical points worth knowing:

Risk factors are checkable, not guesswork. Carrying excess weight around the abdomen, a family history of type 2 diabetes, South Asian, Black or mixed ethnicity, polycystic ovary syndrome, or a history of gestational diabetes all raise risk — a GP can assess this alongside a simple HbA1c or fasting glucose blood test.

Symptoms are easy to miss at this age. Increased thirst, needing to urinate more often, persistent tiredness, blurred vision or slow-healing cuts can all be dismissed as stress or poor sleep in your 20s and 30s. If several of these persist together, it’s worth getting checked rather than waiting.

Prevention evidence is genuinely encouraging. NHS Diabetes Prevention Programme data and wider research consistently show that for people with prediabetes, a combination of dietary changes (particularly reducing ultra-processed food and refined sugar), regular movement and, where relevant, modest weight loss can meaningfully lower the chance of progressing to type 2 diabetes — and can sometimes bring blood sugar back into a normal range entirely.

The takeaway

Type 2 diabetes under 40 is rising faster in the UK than at any other life stage, and the reasons are a mix of diet, inactivity and deprivation rather than any single personal failing. What matters practically is that the earlier this is caught, the more room there is to act — through diet, movement, and in some cases medical support — before complications have a chance to build up over decades rather than years.

This article is for general information only and isn’t a substitute for personalised medical advice. If you’re worried about your risk or are experiencing possible symptoms, speak to your GP, who can arrange the right tests and support for your circumstances.

FAQs

Is type 2 diabetes actually becoming more common in people under 40 in the UK?

Yes. NHS-linked data shows diagnoses in under-40s rose around 40–47% in recent years (varying by sex and time period studied), compared with roughly 22–25% in older adults, and around 164,000–168,000 under-40s in the UK are now living with the condition.

Why is type 2 diabetes rising fastest in young women specifically?

Diabetes UK’s most recent analysis found diagnoses in women under 40 rose 47% between 2017/18 and 2023/24, more than double the rise seen in older women. The exact reasons are still being researched, but hormonal factors, polycystic ovary syndrome, and pregnancy-related glucose changes are thought to play a role alongside the wider dietary and lifestyle drivers affecting all young adults.

Is the rise just down to obesity?

Weight is a major factor, but not the whole picture. Research shows ultra-processed food intake raises type 2 diabetes risk even after accounting for body weight, and deprivation, inactivity and limited access to fresh food all contribute independently.

What are the early warning signs of type 2 diabetes in your 20s or 30s?

Persistent thirst, needing to urinate more than usual (especially at night), ongoing tiredness, blurred vision, and cuts or infections that heal slowly are the most common early signs. Many people have no obvious symptoms at all, which is why testing matters if risk factors apply.

How is type 2 diabetes diagnosed?

A GP can arrange a blood test — usually HbA1c, which reflects average blood sugar over roughly three months, or a fasting glucose test. Results in the “prediabetes” range mean action now can often prevent progression to full type 2 diabetes.

Is youth-onset type 2 diabetes more serious than diabetes diagnosed later in life?

Evidence from the long-running TODAY study suggests it can progress faster and lead to complications earlier, partly because of more years living with elevated blood sugar and partly due to differences in how the condition behaves at younger ages. This makes early detection and management particularly valuable.

Can type 2 diabetes be reversed?

For some people, particularly when caught early and supported by significant dietary change and weight loss, blood sugar can return to a non-diabetic range — sometimes called remission. This isn’t guaranteed for everyone and should be pursued with medical guidance, not self-managed alone.

Who is most at risk of developing type 2 diabetes under 40?

Risk is higher for people with a family history of type 2 diabetes, those carrying more weight around the abdomen, people of South Asian, Black or mixed ethnicity, those with polycystic ovary syndrome or a history of gestational diabetes, and those living in more deprived areas — Diabetes UK data shows children in the most deprived UK areas are around five times more likely to develop it.

What can I actually do to lower my risk right now?

Reducing ultra-processed food and sugary drinks, building in regular movement (even walking counts), prioritising sleep, and getting a blood sugar check if risk factors apply are the most evidence-backed steps. None of these need to be extreme to make a measurable difference over time.

Should I ask my GP for a diabetes test even without symptoms?

If you have any known risk factors — family history, ethnicity-linked risk, PCOS, previous gestational diabetes, or carrying excess weight — it’s reasonable to ask for a check even without symptoms, since type 2 diabetes can develop silently for years before it’s noticed.