Lowering your A1C is achievable through a combination of dietary changes, regular exercise, weight management, and better sleep. Most people see measurable improvement within three months, which is the minimum window for an A1C retest to reflect lifestyle changes. How aggressively you need to act depends on where you’re starting: an A1C between 5.7% and 6.4% falls in the prediabetes range, while 6.5% or higher indicates diabetes.
What Your A1C Actually Measures
A1C reflects your average blood sugar over roughly three months. Glucose in your bloodstream sticks to hemoglobin, the protein inside red blood cells that carries oxygen. The more sugar circulating in your blood, the more hemoglobin gets coated. Since red blood cells live about three months before your body replaces them, an A1C test captures a rolling average of your blood sugar during that entire lifespan.
This is why you can’t cram for an A1C test. A few good days won’t move the number. Sustained changes over weeks and months will. It also means the most recent weeks weigh slightly more heavily in the result, since your newest red blood cells have had the most recent exposure. Most people with diabetes get tested at least twice a year, and retesting sooner than three months won’t give you an accurate picture of your progress.
Change What You Eat
Diet is the single most direct lever you have over blood sugar. Two patterns have strong evidence behind them: low-carbohydrate eating and the Mediterranean diet. A Stanford Medicine study comparing the two found that both improved blood glucose control, with similar drops in A1C (9% relative reduction on a keto-style plan and 7% on Mediterranean). The keto approach produced slightly better numbers, but the Mediterranean diet was easier for people to stick with long-term, which matters more than short-term results.
You don’t need to follow either plan rigidly. The underlying principle is the same: reduce refined carbohydrates (white bread, sugary drinks, pasta, pastries) and replace them with vegetables, lean proteins, healthy fats, and high-fiber foods. Soluble fiber is particularly useful because it slows how quickly carbohydrates raise your blood sugar after a meal. Aim for 6 to 8 grams of soluble fiber daily. Good sources include oats, beans, lentils, apples, and flaxseed.
Carbohydrate quality matters as much as quantity. Swapping white rice for brown rice, choosing whole-grain bread over white, and eating fruit instead of drinking juice are changes that add up over three months without requiring a dramatic overhaul of your meals.
Exercise Consistently
Physical activity pulls glucose out of your bloodstream and into your muscles, both during and after a workout. What’s surprising is how well resistance training performs. In one clinical trial, people with type 2 diabetes who did resistance training for four months lowered their A1C from 8.3% to 7.1%, a full 1.2-point drop. The group doing only aerobic exercise saw a smaller, statistically insignificant improvement.
That doesn’t mean you should skip cardio. Combining resistance training with aerobic exercise and modest weight loss produced a 1.2% A1C reduction compared to just 0.4% with weight loss alone. The combination works better than any single approach. Current guidelines recommend at least 150 minutes of moderate aerobic exercise per week (brisk walking, cycling, swimming) plus resistance training on two or three days, hitting all major muscle groups with 8 to 15 repetitions per exercise.
If you’re starting from zero, even short daily walks after meals can blunt post-meal blood sugar spikes. Build from there. Consistency over months matters far more than intensity in any single session.
Lose a Modest Amount of Weight
You don’t need to reach an ideal body weight to see results. Losing just 5% of your body weight (10 pounds for a 200-pound person) has been linked to about a half-point drop in A1C. Losing 10% can lower it by as much as 1.5 points. That’s a significant shift, potentially enough to move someone from a diabetes-range A1C back into prediabetes territory.
The weight loss itself doesn’t need to come from a specific diet. What matters is a sustained caloric deficit over time. The dietary and exercise strategies above naturally support weight loss, which is one reason their effects on A1C are so strong: they’re working through multiple pathways at once.
Prioritize Sleep and Manage Stress
Sleep deprivation raises cortisol, a stress hormone that directly increases blood sugar. Over time, chronically poor sleep pushes A1C higher even if your diet and exercise habits are solid. Research on adults with diabetes found that sleeping fewer than seven hours a night was associated with higher A1C, and that stress was a significant independent factor driving those numbers up in the short-sleep group.
Alcohol also showed up as a contributor in that research. People who drank regularly had higher A1C than those who didn’t, separate from other factors. If you’re working to bring your number down, cutting back on alcohol gives you a dual benefit: fewer empty calories and less direct disruption of blood sugar regulation.
Stress management doesn’t require meditation retreats. Even simple, consistent habits like a regular sleep schedule, brief daily walks, or limiting screen time before bed can lower cortisol enough to make a measurable difference over three months.
Use Glucose Monitoring to Your Advantage
Continuous glucose monitors (CGMs), the small sensors worn on the arm or abdomen that track blood sugar in real time, help people lower their A1C by about 0.3 percentage points compared to traditional finger-stick testing. That might sound modest, but the real value of CGMs is behavioral. When you can see your blood sugar spike 30 minutes after eating a bagel but stay flat after eggs and avocado, you learn which foods and habits work for your body specifically.
A meta-analysis of randomized controlled trials found that both real-time CGMs and flash glucose monitors produced nearly identical A1C reductions (0.34% and 0.33%, respectively). If you have insurance coverage or can access one through your provider, the feedback loop between what you eat, how you move, and what happens to your blood sugar is one of the most powerful tools for sustained behavior change.
Supplements With Some Evidence
A few supplements have clinical data worth knowing about, though none replace diet and exercise. Berberine has the strongest case: a meta-analysis found it comparable to some oral diabetes medications for lowering blood sugar, A1C, and triglycerides, typically at doses of 500 to 1,500 mg per day split into multiple doses. Chromium supplementation has also shown statistically significant A1C reductions in people with type 2 diabetes. Cinnamon (1 to 6 grams daily) has shown some ability to lower fasting blood sugar, though results are less consistent.
Magnesium is worth considering if your levels are low, which is common in people with type 2 diabetes. Supplementation in that group has been shown to improve insulin sensitivity. These are supporting players, not substitutes for the bigger interventions. And because supplements can interact with diabetes medications, they’re worth discussing with whoever manages your prescriptions.
What a Realistic Timeline Looks Like
Because A1C captures a three-month average, you need at least that long before retesting. But changes in daily blood sugar start within days of adjusting your diet and activity level. If you’re checking fasting glucose or using a CGM, you’ll likely see improvements within the first two weeks, which can be motivating even before your next A1C draw.
A reasonable expectation for someone making consistent lifestyle changes is a 0.5 to 1.5 point drop over three to six months, depending on where you started and how many changes you make simultaneously. For context, the standard first-line diabetes medication reduces A1C by about 1.1 points on average. Combining diet, exercise, modest weight loss, and better sleep can match or exceed that, particularly for people whose A1C is in the prediabetes or early diabetes range. The key word is “combining.” No single change is as powerful as stacking several together.