Practitioners can miss the patient who has prediabetes. Diabetes is epidemic, and the numbers keep rising. The prevention of Type 2 Diabetes (DM2) is a health priority, as important as vaccination policies. Diabetologists recognise that when DM2 is diagnosed, ‘the clock starts ticking’ – it is a progressive condition where insulin resistance and declining insulin secretion often necessitates regular escalation of treatment, to achieve glycaemic control, and to prevent long-term complications.
How to recognise the prediabetic?
Most have features of the metabolic syndrome, including abdominal obesity, hypertension, and a specific dyslipidaemia (high triglycerides, low HDL-cholesterol). Many have a clear family history of DM2. Some show previous laboratory tests highly suspicious of diabetes but these are often dismissed as “borderline” or “mild”. The occasional high blood sugar reading is overlooked as “incidental”. Particularly high-risk females are those with a past history of gestational diabetes (or big babies), and those with PCOS. These patients must have a structured follow-up.
If the laboratory reports “impaired fasting glucose” (IFG is a plasma glucose of > 6.1 mmol/L), or “impaired glucose tolerance” (IGT is a 2-hour GTT plasma glucose of 7.9–11.0 mmol/L), or an intermediate glycated haemoglobin (HbA1c in the range 6.1%–6.4%), the clock is ticking. HbA1c levels of >6.5% are considered to indicate diabetes.
Prediabetes responds to vigorous clinical interventions, predominantly supervised change in lifestyle including dietary intervention to achieve weight loss (restrict total calories, saturated fat and alcohol, and refined carbohydrate), plus disciplined exercise (30 to 60 minutes daily).
In populations where progression from prediabetes (IFG and/or IGT) was about 10% annually, controlled clinical trials of diet and exercise over 3 to 6 years achieved risk reductions of 42% (China), 58% (Finland), and 58% (USA). Drug therapy will provide additional risk reduction (metformin 25%, acarbose 25%, orlistat 25%). There appears to be a huge potential for the use of the new GLP-1 agonists (ByettaTM, BydureonTM, or SaxendaTM by injection) to improve the impaired glucose metabolism and the overweight of prediabetic subjects, but no clinical trial data is available yet.
Ideally the prevention of diabetes should be a public health responsibility, with education, health promotion, and support for healthy lifestyle programs. At present, the burden of effective intervention is in general practice.
Welborn TA. Diagnostic and screening tests for diabetes and its precursors. Medicographia 2004: 26; 29-34
Barry Eleanor et al. Efficacy and effectiveness of screen and treat policies in prevention of type 2 diabetes: Systematic review and meta- analysis of screening tests and interventions. BMJ 2017: 356; i 6538
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