Lowering your A1C is about bringing down your average blood sugar over two to three months. An A1C of 5.7% corresponds to an average blood sugar around 120 mg/dL, while an A1C of 8% means your blood sugar has been averaging roughly 183 mg/dL. The good news: a combination of dietary changes, regular movement, and weight management can lower A1C by 1% or more, which is enough to meaningfully reduce your risk of complications.
What A1C Actually Measures
A1C reflects how much sugar has attached to the hemoglobin inside your red blood cells. Since red blood cells live roughly 90 to 120 days, the test captures a rolling average of your blood sugar over the past two to three months rather than a single snapshot. That’s why one good week of eating won’t change the number, and why one bad week won’t ruin it either. It’s a trend line, not a daily grade.
If your A1C is currently 7.0%, your blood sugar has been averaging about 154 mg/dL. At 9.0%, that average jumps to around 212 mg/dL. You can estimate your own average using a simple formula: multiply your A1C percentage by 28.7, then subtract 46.7. The result is your estimated average glucose in mg/dL.
One thing worth knowing: factors beyond blood sugar can nudge A1C readings up or down. Conditions that shorten or lengthen the lifespan of your red blood cells (like certain anemias) can skew results. If your A1C seems out of step with what your daily glucose readings show, that discrepancy is worth raising with your doctor.
Cut Refined Carbs and Add Fiber
Dietary changes deliver some of the largest A1C reductions outside of medication. In clinical studies, people with type 2 diabetes who switched to a low-carbohydrate, higher-fat diet saw their A1C drop by an average of 1.29% compared to those receiving usual care. The effect is strongest in the first two months, where reductions averaged 1.38%, then gradually settled to about 0.55% by four months as people adapted or loosened adherence.
You don’t necessarily need to go very low-carb to see benefits. The core principle is replacing refined carbohydrates (white bread, sugary drinks, processed snacks) with foods that release glucose more slowly. Vegetables, legumes, nuts, and whole grains all fit this approach. Fiber plays a direct role here: the Dietary Guidelines for Americans recommend 22 to 34 grams of fiber per day depending on your age and sex, and most Americans fall well short of that. Soluble fiber, found in oats, beans, and many fruits, slows the absorption of sugar after meals.
Practical starting points that tend to stick: swap sugary breakfast cereals for eggs or oatmeal, replace white rice with cauliflower rice or a smaller portion of brown rice, and make half your plate non-starchy vegetables at dinner. Small, consistent changes sustained over three months will show up on your next A1C test.
Move After Meals (and Throughout the Day)
Exercise lowers A1C through two mechanisms: your muscles burn glucose during activity, and regular training makes your cells more responsive to insulin over time. A meta-analysis of 27 studies found that exercise training reduced A1C by an average of 0.80%. That’s comparable to some medications.
The best results come from combining aerobic exercise (walking, cycling, swimming) with resistance training (weight lifting, resistance bands, bodyweight exercises). In the DARE trial, the first well-powered study to compare these head to head, the combination group saw their A1C drop by 1.0%, compared to 0.5% for aerobic-only and 0.4% for resistance-only. If you’re choosing one, either type helps. If you can do both, the payoff is roughly double.
Timing matters more than most people realize. Research published in the Journal of Applied Physiology found that brief, periodic movement throughout the day was more effective at lowering post-meal blood sugar spikes than a single exercise session before or after eating. Participants who did short bursts of activity (about four minutes every 30 minutes) kept their peak blood sugar under 100 mg/dL after breakfast, compared to 109 to 115 mg/dL with pre- or post-meal exercise sessions. Even walking for under two minutes every 30 minutes has been shown to lower blood sugar over the course of a full day. If a structured workout isn’t possible, simply getting up and moving regularly throughout the day still helps.
Lose 5 to 10% of Your Body Weight
Weight loss and A1C are tightly connected, especially if you carry extra weight around the midsection. Both the Finnish Prevention Study and the Diabetes Prevention Program demonstrated that a lifestyle intervention including at least 5% body weight loss reduced the risk of progressing from prediabetes to diabetes by 58%. For someone who weighs 200 pounds, that’s a loss of 10 pounds.
The A1C reductions from weight loss alone tend to be modest, but they compound with the dietary and exercise changes that usually accompany them. Most people using lifestyle interventions can realistically expect to lose 5 to 10% of their starting weight, which is the range where metabolic benefits become significant. Crash diets that produce rapid weight loss rarely sustain those numbers on the next A1C test. Steady, gradual loss over months is what moves the needle and keeps it there.
Sleep and Stress Are Not Optional
Sleeping fewer than seven hours a night is independently associated with higher A1C levels. The mechanism is straightforward: insufficient sleep raises cortisol, a stress hormone that triggers your liver to release more glucose and makes your cells less responsive to insulin. Over weeks and months, this pushes your average blood sugar up.
Stress operates through the same cortisol pathway. In studies of adults with diabetes, those who slept under seven hours reported higher stress levels, and stress was a significant factor driving their elevated A1C. Sleep and stress reinforce each other in a cycle: poor sleep increases stress, and high stress disrupts sleep. Breaking the cycle on either end helps. Prioritizing seven to nine hours of sleep, maintaining a consistent bedtime, and limiting screen time before bed are changes that cost nothing and can quietly support every other effort you’re making.
Supplements With Some Evidence
A few supplements have shown modest blood sugar-lowering effects in clinical trials, though none replace dietary and lifestyle changes. Berberine, a compound found in several plants, has the most consistent evidence. In a randomized trial, participants taking 1,200 mg of berberine daily combined with 600 mg of cinnamon for 12 weeks had significantly lower fasting blood sugar and A1C compared to placebo.
Cinnamon on its own has mixed results across studies, with some showing small benefits and others showing none. The type matters: Ceylon cinnamon is generally preferred over cassia cinnamon for supplementation because cassia contains higher levels of a compound that can stress the liver at high doses. If you’re considering any supplement, treat it as a possible small addition to the strategies above, not a substitute for them.
How Often to Check Your Progress
Because A1C reflects a two- to three-month average, testing more frequently than every three months won’t give you meaningful new information. The CDC recommends testing every three months if your treatment has changed or you’re not meeting your blood sugar goals, and every six months once your numbers are stable and on target. That three-month window also means any changes you make today won’t fully show up on a test taken next week. Give new habits at least 8 to 12 weeks before judging whether they’re working.
If you use a home glucose meter or continuous glucose monitor, daily readings can fill the gap between A1C tests. Watching your post-meal numbers come down after you start walking after dinner or cutting back on refined carbs gives you real-time feedback that the A1C test will eventually confirm.