Diabetes risk and what to do about it early

Type 2 diabetes develops over years, produces few symptoms until it is established, and is one of the few conditions where the pre-clinical stage has strong trial evidence for intervention.

How it is measured

HbA1c reflects average glucose over the preceding two to three months and is the most commonly used test, requiring no fasting.

Fasting glucose and oral glucose tolerance testing are also used.

Thresholds differ slightly between guidelines, with diabetes generally diagnosed at an HbA1c of 48 mmol/mol or 6.5 per cent, and an intermediate range below that defining prediabetes or non-diabetic hyperglycaemia.

HbA1c is unreliable in some situations — anaemia, haemoglobin variants, pregnancy, recent transfusion and kidney disease — where alternative tests are used.

Who should be tested

Risk-based rather than universal in most guidance.

Higher risk with increasing age, higher body weight, particularly central adiposity, family history, certain ethnic backgrounds where risk is elevated at lower body weight, previous gestational diabetes, polycystic ovary syndrome, hypertension, dyslipidaemia and physical inactivity.

Risk calculators are freely available and take a couple of minutes.

Symptoms warranting immediate testing: excessive thirst, frequent urination, unexplained weight loss, fatigue, blurred vision, recurrent infections and slow-healing wounds.

The evidence for prevention

Unusually strong for a lifestyle intervention.

Large randomised trials of intensive lifestyle programmes in people with prediabetes have shown substantial reductions in progression to diabetes, outperforming metformin in the same trials.

Long-term follow-up has shown persistent benefit years after the programmes ended.

The components: modest weight loss, increased physical activity to around the guideline levels, and dietary change.

The weight loss target in these trials was around five to seven per cent of body weight — a modest and achievable figure that is frequently misrepresented as requiring dramatic transformation.

National diabetes prevention programmes based on this evidence operate in several countries and are free to eligible people, and referral is under-used.

Remission

A more recent and important finding.

Trials of intensive weight management, including low-energy total diet replacement followed by structured food reintroduction, have achieved remission of type 2 diabetes in a substantial proportion of participants, with remission related to the degree of weight loss and to duration since diagnosis.

Remission means normal glucose levels without glucose-lowering medication, and it is not the same as cure — relapse occurs with weight regain and monitoring continues.

These programmes require medical supervision, particularly for anyone on glucose-lowering or blood pressure medication, since doses need adjusting.

What to do practically

The components that matter.

Weight, where modest loss produces disproportionate metabolic benefit.

Physical activity, including both aerobic activity and resistance training, which improves insulin sensitivity independently of weight change.

Diet: reducing free sugars and refined carbohydrates, increasing fibre, and following a dietary pattern with evidence such as Mediterranean-style eating.

No single dietary approach has demonstrated clear superiority for prevention, and adherence is the dominant factor.

Sleep, where short and poor sleep are associated with insulin resistance.

Stopping smoking.

And reducing alcohol.

If you already have diabetes

Where the checks are what prevent the expensive complications.

Annual retinal screening, which prevents avoidable blindness and is one of the highest-value checks in medicine.

Annual foot check, since neuropathy and vascular disease combine to produce ulceration and, if unaddressed, amputation.

Kidney function and urine albumin testing.

Blood pressure and lipids, where treatment thresholds are lower.

HbA1c at agreed intervals.

Dental review, given the bidirectional relationship with periodontal disease.

And structured education programmes, which are offered free in many systems and attended by a minority.

The cost picture

Which is stark.

Diabetes accounts for a very large share of health spending in most countries, with the majority going on complications rather than on the condition itself.

Amputations, dialysis, blindness and cardiovascular events are the expensive endpoints, and they are the ones the routine checks prevent.

Which means that the annual eye and foot check — free in many systems and skipped by many patients — is among the best-value appointments available.

Metformin, the first-line medication, is generic and costs very little.

Newer agents including GLP-1 receptor agonists and SGLT2 inhibitors are considerably more expensive and have cardiovascular and kidney benefits that justify their use in specific groups.

General information only, not medical advice. Consult a qualified clinician about diabetes risk, testing and treatment, and attend all offered screening if you have diabetes.