Waiting until diabetes feels obvious can mean waiting longer than you realise. The International Diabetes Federation (IDF) estimates that 251.7 million adults aged 20–79 had undiagnosed diabetes worldwide in 2024. That was 42.8% of adults living with diabetes—more than four in ten.

The uncomfortable question is simple: if a condition can remain unnoticed, what are you waiting to feel? A normal working day, an ordinary appetite or the ability to keep up with family life cannot tell you what a laboratory test would show.

World Diabetes Day falls on 14 November. Its 2026–2027 theme, “Early action on diabetes,” focuses on earlier diagnosis and reducing risk. The figures below explain why a concern about diabetes deserves a practical next step rather than another indefinite delay.

Worldwide in 2024, 42.8% of adults aged 20–79 living with diabetes were undiagnosed.

589 million in 2024; 853 million projected by 2050

The IDF puts the 2024 global total at approximately 589 million adults aged 20–79, or 11.1% of that age group—roughly one in nine. Its 2050 projection is 853 million, about 45% higher. Using the rounded headline totals, that is approximately 264 million additional adults.

These estimates cover all forms of diabetes. The 2050 figure uses IDF modelling to project future cases. For readers, the immediate task is practical: understand your own risk, raise concerns with a healthcare professional and complete any testing that is recommended.

The IDF projects about 45% growth in adults aged 20–79 with diabetes between 2024 and 2050.

The diagnosis gap is larger in lower-income countries

In the IDF’s 2024 estimates, the undiagnosed share was 58.7% in low-income countries, 45.5% in middle-income countries and 28.9% in high-income countries. In every case, the denominator is adults aged 20–79 who already had diabetes, rather than the whole population.

A national average helps describe the scale of the problem. Your next step depends on the care you can access, the tests you have already had and the personal risk factors your clinician identifies. Bring previous reports to the appointment and ask whether follow-up is overdue.

Undiagnosed diabetes was estimated at 58.7%, 45.5% and 28.9% across country income groups in 2024.

For some people, complications appear before the diagnosis

The World Diabetes Day campaign reports that up to 50% of people with type 2 diabetes have complications at diagnosis. A first diagnosis may therefore involve more than confirming high glucose: the healthcare team may also need to assess damage that has already developed. Feeling well is a poor reason to keep postponing a recommended assessment.

The World Health Organization explains that type 2 diabetes symptoms can be mild and remain unnoticed for years. Diabetes can affect the heart, eyes, kidneys and nerves. Persistent thirst, frequent urination or unexplained weight loss therefore deserve medical assessment, even when it is tempting to explain them away.

The wider burden is substantial. The IDF estimated 3.4 million diabetes-attributable deaths among adults aged 20–79 in 2024 and more than US$1 trillion in global diabetes-related healthcare spending that year. Managing diabetes can involve ongoing medicines, monitoring and treatment of complications. The scale of that burden reinforces the importance of prevention, timely diagnosis and continuing care.

Early treatment has evidence behind it, too

Finding diabetes is only useful when the result leads to appropriate care. In the UK Prospective Diabetes Study (UKPDS), 4,209 people with newly diagnosed type 2 diabetes were randomised to conventional or intensive glucose-control strategies. The 10-year post-trial follow-up, published in 2008, reported the following outcomes for the group originally assigned to intensive treatment with a sulfonylurea or insulin:utcome

Relative reduction versus conventional treatment

These are relative reductions, not percentage-point changes or benefits guaranteed to every patient. UKPDS tested treatment after diagnosis; it does not show that a screening appointment alone produces these effects. The practical lesson is to connect a diagnosis with sustained care and individual treatment goals, rather than treating the test as the end of the process.

Three laboratory thresholds worth understanding

The American Diabetes Association’s 2026 Standards of Care list these diagnostic thresholds for nonpregnant people:

HbA1c reflects average glucose over approximately three months, according to NIDDK. A fasting plasma glucose test requires at least eight hours without caloric intake. The two-hour value above applies to a standardised glucose tolerance test, rather than an ordinary meal or a home reading.

Continuous glucose monitoring (CGM) shows glucose trends throughout the day, helping users visualise their glucose responses before and after meals and exercise and use this information to guide everyday food and activity choices. Where CGM is appropriate, these continuous data can also help healthcare professionals understand glucose patterns and develop more personalised management plans, providing a clearer basis for daily care. Diabetes should be diagnosed by a doctor using standardised laboratory testing alongside clinical assessment.

Make early action specific enough to happen

Who should be tested depends on personal risk and local guidance. As one example, the US Preventive Services Task Force recommends screening asymptomatic, nonpregnant adults aged 35–70 who have overweight or obesity. It says a three-year interval may be reasonable after a normal result. Your local guidelines and medical history may lead to a different starting age or interval.

An earlier assessment may be appropriate for some people. Tell your clinician about a family history of type 2 diabetes, previous gestational diabetes, earlier abnormal results or symptoms that concern you. Ask which assessment fits your situation and when it should happen.

Before leaving the appointment, make sure you know which test is planned, whether preparation is needed, how you will receive the result and what happens next. Save the report and write down the agreed follow-up date. If you have been told to arrange testing, a few healthier meals or a week of exercise should not become a reason to postpone it.

This World Diabetes Day, give a vague intention a date. Check when you were last assessed, raise the question with a healthcare professional and complete any recommended follow-up. You do not have to wait for diabetes to interrupt daily life before taking it seriously.