Lowering your A1c is achievable through a combination of dietary changes, exercise, and lifestyle adjustments, and you can start seeing measurable progress within about 30 days. A1c reflects your average blood sugar over the lifespan of your red blood cells, which live roughly 80 days on average. That means changes you make today will begin showing up in your next lab result, with about 50% of the improvement visible within a month and 80% within two months.
A normal A1c is below 5.7%. The prediabetes range falls between 5.7% and 6.4%, and an A1c of 6.5% or higher indicates diabetes. Where you start matters: people with a baseline A1c of 9% or above tend to see the most dramatic drops (averaging 2.5 percentage points) from lifestyle changes, while those starting between 6.5% and 8% typically see a reduction of about 0.5 percentage points with similar effort.
Why Your Starting Point Matters
A1c improvement isn’t purely proportional to how hard you try. A 13-year observational study of intensive lifestyle interventions found that participants with the highest starting A1c values saw the largest reductions, even when the amount of weight they lost was identical to those who started lower. People beginning at 9% or above dropped an average of 2.5 points. Those starting between 8% and 9% dropped about 1.2 points. And those between 6.5% and 8% dropped roughly half a point. The weight loss across all three groups was statistically the same.
This doesn’t mean effort is wasted if your A1c is already in the lower range. It means your expectations should be calibrated. A 0.5-point drop from 7.2% to 6.7% is clinically significant and reduces your risk of complications. But you shouldn’t feel discouraged if your number moves slowly compared to someone who started much higher.
Adjust What and How You Eat
Dietary changes are the single most controllable lever for A1c reduction. Two well-studied approaches, a ketogenic diet and a Mediterranean-style diet, both lowered A1c by meaningful amounts in a head-to-head crossover trial. After 12 weeks, the ketogenic diet reduced A1c by about 9%, while the Mediterranean diet reduced it by about 7%. The difference between the two wasn’t statistically significant, which suggests the best diet is the one you can actually sustain.
Both approaches share key principles: they limit refined carbohydrates, emphasize whole foods, and include healthy fats. The Mediterranean diet tends to be easier to maintain long-term because it’s less restrictive, allowing whole grains, legumes, and fruit. A ketogenic approach can produce faster initial results but requires strict carbohydrate limits that many people find difficult to keep up.
Beyond choosing a dietary pattern, increasing your fiber intake delivers A1c improvements that rival some medications. Diets rich in soluble fiber (up to about 42 grams per day from food, or 13 to 15 grams per day from supplements) have reduced A1c by roughly 5% in studies of people with type 2 diabetes. Psyllium husk is one of the most studied options: 10 to 14 grams daily produced significant reductions in A1c, fasting blood sugar, and insulin resistance within 8 to 12 weeks. Inulin, a fiber found in chicory root and available as a supplement, showed similar benefits at doses around 10 grams per day over at least six weeks. Soluble fiber works by forming a gel in your digestive tract that slows the absorption of sugar into your bloodstream, blunting the post-meal glucose spikes that drive A1c upward.
Combine Cardio and Strength Training
Exercise lowers A1c through several pathways: it makes your muscles absorb glucose without needing as much insulin, it depletes stored sugar in muscle tissue (creating demand for more), and over time it improves your body’s overall insulin sensitivity. But the type of exercise you do changes how much benefit you get.
A randomized trial comparing aerobic training, resistance training, and a combination of both found that doing both together was substantially more effective. Aerobic training alone lowered A1c by about 0.51 percentage points compared to no exercise. Resistance training alone lowered it by about 0.38 points. But combining aerobic and resistance training lowered A1c by an additional 0.46 points beyond aerobic training alone, and 0.59 points beyond resistance training alone.
In practical terms, this means a weekly routine that includes both brisk walking, cycling, or swimming alongside some form of strength work (weights, resistance bands, or bodyweight exercises) will produce roughly double the A1c benefit of doing only one type. You don’t need extreme intensity. Consistency across both categories is what drives the result.
Prioritize Sleep Quality
Poor sleep raises blood sugar through a hormonal cascade that’s difficult to override with diet and exercise alone. People with type 2 diabetes who report greater sleep problems have significantly higher cortisol levels throughout the day, with especially elevated levels in the evening. Cortisol directly raises blood sugar by triggering the liver to produce glucose and by reducing insulin sensitivity at the cellular level. It also impairs insulin secretion from the pancreas itself.
What makes this especially problematic is that chronic sleep disruption also blunts your cortisol stress response, meaning your body loses the ability to properly regulate the hormone in both directions. You end up with higher baseline cortisol (raising fasting glucose) and a less effective stress recovery system. Improving sleep hygiene, maintaining a consistent sleep schedule, keeping your room cool and dark, and addressing issues like sleep apnea (which is extremely common in people with elevated A1c) can create measurable improvements in blood sugar that show up on your next lab draw.
Stay Well Hydrated
Dehydration raises blood sugar through a mechanism that most people aren’t aware of. When your body is low on water, it releases a hormone called vasopressin to help retain fluid. Vasopressin also triggers your liver to produce glucose and stimulates the release of glucagon, another hormone that raises blood sugar. Vasopressin receptors sit on both liver cells and the insulin-producing cells of your pancreas, giving it a direct line to your glucose regulation system.
Research published in Diabetes Care found a plausible causal link between low water intake and the development of high blood sugar, noting that vasopressin levels rise in proportion to how dehydrated you are. While there isn’t a precise number of glasses per day that maps to an A1c reduction, chronic mild dehydration creates a background state of elevated glucose production that works against everything else you’re doing. Drinking water consistently throughout the day, especially before and after meals, removes one unnecessary obstacle to blood sugar control.
Track Progress With the Right Tools
A1c is measured through a blood draw, typically every three months. But if you want real-time feedback on how your daily choices affect blood sugar, a continuous glucose monitor (CGM) can bridge the gap between lab visits. CGMs measure glucose every few minutes and report a metric called “time in range,” which tracks the percentage of the day your blood sugar stays between 70 and 180 mg/dL.
Time in range correlates strongly with A1c, with a correlation coefficient of about 0.91 in studies. Increasing your time in range directly translates to a lower A1c at your next test. The practical value of a CGM is that it shows you, in real time, which meals spike your glucose, how exercise brings it down, and how sleep quality affects your morning readings. This turns A1c management from a guessing game into a feedback loop. CGMs are available by prescription and increasingly covered by insurance for people with diabetes, though some models are now available over the counter.
What Medications Can Add
When lifestyle changes aren’t enough on their own, medications can provide an additional push. The most commonly prescribed first-line medication for type 2 diabetes typically reduces A1c by 1 to 1.5 percentage points. Newer injectable medications that mimic a gut hormone involved in blood sugar regulation (GLP-1 receptor agonists) lower A1c by 0.8 to 1.6 percentage points on average. Another class of medications that works through the kidneys to remove excess sugar through urine (SGLT2 inhibitors) produces reductions of 0.5 to 1.0 percentage points.
These medications work through entirely different mechanisms than lifestyle changes, which means the effects can stack. Someone who combines dietary improvements, exercise, and medication will generally see a larger total reduction than any single approach alone. The choice of medication depends on your specific health profile, other conditions you may have, and how your body responds, all of which your prescriber will factor in.
A Realistic Timeline
Because red blood cells live an average of 80 days and A1c reflects the glucose attached to them over their lifespan, your A1c is a weighted average that favors recent weeks more heavily than older ones. About 50% of a change in blood sugar control shows up in your A1c within 30 days. By 50 to 70 days, you’ll see roughly 80% of the change reflected. This is why A1c is retested every three months: it takes that long for the full picture to update.
If you start making changes today, your next A1c test in three months will capture nearly all of that improvement. But the half-life of roughly 30 days also means backsliding shows up quickly. A two-week vacation of poor eating won’t erase months of progress, but a sustained return to old habits will shift the number within a month. The biology rewards consistency more than perfection.