Prediabetes: How to Reverse It Before It Becomes Type 2 Diabetes

The American Diabetes Association (ADA), in its Standards of Care in Diabetes, defines prediabetes through three independent criteria — meeting just one is enough for a diagnosis. In clinical practice, fasting glucose and glycated hemoglobin (HbA1c) are used most often; the oral glucose tolerance test (OGTT) is more sensitive but less convenient for routine screening.

It's worth remembering that these three criteria don't always align in the same person — someone can have elevated fasting glucose with normal HbA1c, or vice versa. That's why, at borderline results, doctors sometimes order more than one test before confirming or ruling out the diagnosis. HbA1c reflects average blood sugar over roughly the past three months, making it less sensitive to a single day's fluctuation than one fasting glucose reading.

Critics of this kind of study often ask whether a short-term intervention's effect actually persists, or merely postpones the inevitable by a few years. The answer came from the DPP's continuation — the Diabetes Prevention Program Outcomes Study (DPPOS), which followed 2,776 people (88% of the original cohort) for a combined 15 years.

This is a crucial complement to the original result: the effect of lifestyle change wasn't a temporary postponement of the problem but a lasting shift in risk trajectory across a decade and beyond. Interestingly, over the longer term the gap between metformin and placebo stayed stable, while the advantage of lifestyle intervention alone, though still clear, narrowed somewhat from the initial 58% — consistent with the observation that some participants gradually drifted back toward old habits over time.

Prediabetes most often stems from insulin resistance — a state in which muscle, liver, and fat-tissue cells respond less and less to insulin's signal, even though the hormone itself isn't in short supply. For a while, the pancreas compensates by producing more and more insulin to keep glucose normal. Prediabetes appears at the point where that compensation starts to fail, and blood sugar begins creeping up despite high insulin output.

Excess visceral fat — the kind that accumulates around abdominal organs rather than under the skin — plays a particular role in this process, because it secretes pro-inflammatory substances that further worsen insulin resistance at the cellular level. This is one reason weight loss, even modest, brings disproportionately large metabolic benefits at this stage: it isn't just about the number on the scale, but a real reduction in visceral fat and the inflammation surrounding it.

Importantly, the DPP intervention wasn't a crash diet or an extreme regimen — it was a structured but fundamentally moderate program of habit change, delivered with regular support. That suggests the key to success here isn't the intensity of any single intervention, but its consistency and long-term maintenance rather than a short, drastic burst of effort.

Metformin isn't the first-line choice for prediabetes — that remains lifestyle change, which proved more effective in the DPP trial. ADA guidelines do, however, identify specific patient groups where adding metformin as a supplement to, not a replacement for, behavioral intervention is worth considering.

Prediabetes is one of the few diagnoses in metabolic medicine where the evidence for behavioral intervention is this strong and this long-term. Fifteen years of DPPOS follow-up is rare in lifestyle research — and it's precisely that length of observation that makes the result credible, rather than just an artifact of short-lived motivation at the start of the program.

If you've received a prediabetes diagnosis, the most important step isn't hunting for a miracle supplement or a restrictive diet, but implementing moderate, consistent changes — ones you can sustain not for a month, but for years. It's also worth not waiting passively for the next check-up, but talking to your doctor about an individualized plan, especially if additional risk factors are in play, such as significant obesity or a history of gestational diabetes.