Prediabetes: What to Eat to Lower Your Risk

Prediabetes means your blood glucose is higher than normal but not yet in the diabetes range. It's usually found incidentally on a routine blood test, and it's frequently delivered as a throwaway line — "your sugar's a bit up, watch your diet" — with no explanation of what that means.

Here's the part worth knowing: prediabetes is one of the few diagnoses where diet and activity have been shown, in large randomised trials, to substantially reduce the chance of progressing to type 2 diabetes. It's a warning with a genuinely good response rate.

What the numbers mean

Two tests are commonly used in Australia. Your GP interprets them in context — these ranges are for orientation, not self-diagnosis.

HbA1c reflects your average glucose over roughly three months, which makes it the more useful number to track — a single fasting reading is easily thrown by a bad night's sleep or a stressful morning.

What's actually driving it

Prediabetes is the visible end of insulin resistance. Your pancreas is compensating by producing more insulin, and glucose is starting to escape that compensation. The mechanism, and what to eat about it, is covered in depth in our insulin resistance diet guide — this page is the same physiology one step further along.

The implication is encouraging: because the pancreas is still compensating, improving insulin sensitivity has somewhere to go. That's why intervention works better at this stage than later.

What the trials actually showed

Large programs including the Diabetes Prevention Program and the Finnish Diabetes Prevention Study tested structured lifestyle change against control, and both found substantial reductions in progression to type 2 diabetes. Notably, in the US trial the lifestyle arm outperformed metformin.

The interventions were unglamorous and consistent:

• Modest weight loss — 5 to 7% of body weight. Not transformation. For someone at 90 kg that's 4.5–6.5 kg, and early loss comes preferentially from visceral and liver fat, which is the metabolically active kind.
• 150 minutes a week of moderate activity. Brisk walking counts.
• Higher fibre, lower saturated fat, less refined carbohydrate.
• Resistance training, because skeletal muscle is where most glucose is disposed of.

How to eat for it

No single named diet wins. What consistently helps is structural, and it applies to whatever pattern you'll actually sustain:

1. Protein at every meal, 25–40 g. See the protein guide for targets.
2. Carbohydrates in whole form, and lower GI. Form matters as much as amount — steel-cut oats behave differently from instant, whole fruit differently from juice. Our low GI foods guide has the practical swaps.
3. Fibre toward 28–38 g a day. Soluble fibre slows glucose absorption directly — see the fibre guide.
4. Never eat carbohydrate alone. Pair it with protein, fat or fibre and the same food produces a flatter curve.
5. Cut sugar-sweetened drinks first. Largest single effect, easiest change.
6. Unsaturated fats over saturated. Olive oil, nuts, seeds, oily fish — the Mediterranean pattern is the best-evidenced whole-diet approach here.

Sleep and stress are not optional extras

Both act directly on glucose, which is why a diet-only approach often underperforms:

• Short sleep measurably reduces insulin sensitivity in healthy people within a few nights. If you're eating well on five hours, sleep is your constraint.
• Chronic stress raises blood glucose directly via cortisol.
• Untreated sleep apnoea worsens insulin resistance and is under-diagnosed. Loud snoring plus daytime exhaustion is worth raising with your GP.

What to track, and how often

Retest HbA1c with your GP at 3 to 6 months — it reflects a three-month average, so testing sooner tells you little. Between tests, waist circumference is a better progress signal than weight, because it tracks the visceral fat that matters most. Our waist-to-height ratio calculator gives you a target in ten seconds.

Resist judging this by the scale weekly. The metabolic markers move first, and they're what you're actually treating.

Where to start

Pick two changes, not ten: remove sugar-sweetened drinks, and add 25–30 g of protein to breakfast. Walk after your largest meal. Book the three-month HbA1c retest now so it's in the diary. Ask your GP whether you qualify for a Chronic Disease Management plan — prediabetes often does, and it unlocks a Medicare rebate for dietitian visits.