A ketogenic diet can produce meaningful improvements in blood sugar control for people with type 2 diabetes, at least in the short term. A meta-analysis published in Nutrition & Diabetes found that ketogenic diets lowered HbA1c by an average of 1.07 percentage points and reduced fasting blood sugar by about 23 mg/dL. Those are clinically significant numbers. But keto also carries specific risks for people on certain diabetes medications, and its long-term advantages over other dietary approaches are less clear.
How Keto Affects Blood Sugar
When you eat very few carbohydrates, your body absorbs less sugar from digestion, which directly lowers the blood sugar spike after meals. With less sugar coming in, your pancreas doesn’t need to produce as much insulin. Over time, this lower insulin demand can improve how well your cells respond to insulin, which is the core problem in type 2 diabetes.
There’s also a secondary mechanism at work. When your liver starts producing ketone bodies for fuel, one of them triggers the release of a hormone from fat tissue called adiponectin. Adiponectin activates a cellular pathway that further improves insulin sensitivity. So keto works on two fronts: it reduces how much insulin your body needs while also making your cells more responsive to the insulin you do produce.
What the Numbers Look Like
In clinical trials, keto consistently outperforms standard diets on several diabetes markers. A meta-analysis of randomized controlled trials in people with type 2 diabetes found that keto significantly lowered HbA1c, reduced triglycerides, and raised HDL (the protective cholesterol). Total cholesterol and LDL did not differ significantly between keto and non-keto groups, which is reassuring given concerns about the diet’s high fat content.
The medication reductions are striking. In one study, after 24 weeks, 95% of people on a low-carb diet reduced or stopped their diabetes medications, compared to 62% on a low-glycemic diet. After a full year, 100% of participants had discontinued sulfonylureas, and 94% had reduced or eliminated insulin. Sixty percent of those who completed the study reached an HbA1c below 6.5% without diabetes medications other than metformin. For many people, the possibility of taking fewer medications is one of the most compelling reasons to try keto.
Weight Loss: Faster but Not Necessarily Greater
Keto tends to produce faster initial weight loss than other approaches, but the gap narrows over time. A study presented by the American Diabetes Association compared a very-low-calorie ketogenic diet to a low-calorie Mediterranean diet and found that both reduced visceral fat (the dangerous fat packed around your organs) by similar amounts. At 5% body weight loss, both groups had shed roughly 28 to 41% of their visceral fat. At 10% loss, the reductions were nearly identical. Both diets also preserved muscle mass equally well.
A comprehensive Cochrane review of randomized trials reached a similar conclusion: there is probably little to no difference in weight loss or cardiovascular risk factors between low-carb and balanced-carb diets at the two-year mark. Keto gets you there faster, but if you’re comparing endpoints rather than speed, the advantage fades.
The Long-Term Picture
Short-term results for keto and diabetes are impressive, but the two-year data tells a more nuanced story. A study tracking a ketogenic diet paired with virtual coaching found that after two years, participants had a significant reduction in BMI and were taking fewer diabetes medications on average. However, HbA1c was no longer significantly different from baseline. This suggests that the dramatic early improvements in blood sugar may not fully persist, potentially because adherence becomes harder or because the body adapts over time.
This is a common pattern with restrictive diets. The first six to twelve months show the strongest results, and then the benefits plateau or partially reverse. That doesn’t mean keto is a failure. Needing fewer medications is a meaningful, lasting benefit even if HbA1c drifts back up somewhat. But it does mean keto isn’t a permanent fix unless you can sustain it long-term, which many people find difficult.
A Serious Risk With SGLT2 Inhibitors
If you take an SGLT2 inhibitor (medications with names ending in “-flozin,” like empagliflozin or dapagliflozin), combining it with a ketogenic diet creates a specific and dangerous risk: euglycemic diabetic ketoacidosis. This is a condition where your blood becomes dangerously acidic even though your blood sugar reads normal or only slightly elevated. Because your glucose isn’t sky-high, it can be missed or diagnosed late.
The FDA has issued warnings about SGLT2 inhibitors and ketoacidosis risk, and low-carbohydrate diets are listed as a precipitating factor. Case reports describe patients hospitalized after combining these medications with keto. The clinical recommendation is straightforward: if you’re on an SGLT2 inhibitor, avoid a ketogenic diet. If you want to try keto, your medication regimen needs to be adjusted first.
Nutritional Ketosis Is Not Ketoacidosis
One common source of confusion is the difference between the ketosis you achieve through diet and the ketoacidosis that can land you in the hospital. They involve the same molecules but at vastly different concentrations. During nutritional ketosis on a ketogenic diet, blood ketone levels typically reach about 4 to 5 millimoles per liter. During diabetic ketoacidosis, ketone levels can surge to 20 to 25 millimoles per liter, four to five times higher. At those extreme levels, ketones overwhelm the body’s ability to buffer acid in the blood, creating a medical emergency. A healthy person following a ketogenic diet won’t reach those levels because even small amounts of insulin keep ketone production in check.
Kidney Health Concerns
Studies lasting three to twelve months have not found that keto harms kidney function. But those studies had limited follow-up and high dropout rates, so they can’t rule out longer-term effects. The bigger concern is for people who already have reduced kidney function, which is common in type 2 diabetes.
Ketogenic diets can worsen metabolic acidosis, a condition where the blood becomes too acidic. Healthy kidneys handle this by excreting more acid, but kidneys that are already compromised have a reduced capacity to do so. Untreated metabolic acidosis has been shown to accelerate kidney function decline. There’s also an increased risk of kidney stones, which has been documented in pediatric patients using keto for epilepsy and may be amplified in people with obesity and insulin resistance, who already have lower urinary pH.
If you have kidney disease, a plant-based version of the ketogenic diet may reduce some of these risks compared to the animal-heavy versions most people follow. But given the limited safety data, people with advanced kidney disease are generally advised to explore other dietary patterns first.
Where Keto Fits Among Your Options
The American Diabetes Association’s 2024 guidelines don’t single out any one diet as best for type 2 diabetes. Instead, they recommend individualized medical nutrition therapy, ideally guided by a registered dietitian. Their emphasis is on minimally processed, high-fiber carbohydrate sources and reducing added sugars and sugary drinks. They acknowledge that low-carb approaches can work but point to evidence showing similar outcomes across dietary patterns at the two-year mark.
Keto is a powerful short-term tool for resetting blood sugar and reducing medications. It works best for people who find carbohydrate restriction easier to maintain than calorie counting, who don’t have significant kidney disease, and who aren’t on SGLT2 inhibitors. If your primary goal is rapid improvement in blood sugar control and you can commit to the dietary changes for at least several months, keto has strong evidence behind it. If you’re looking for a lifelong eating pattern, the evidence suggests that several approaches, including Mediterranean and balanced lower-carb diets, produce comparable results over time. The best diet for your diabetes is ultimately the one you can follow consistently while keeping your numbers in a safe range.