A ketogenic diet can significantly improve blood sugar control in people with type 2 diabetes, and the clinical evidence behind it is strong. In one study of patients with severe type 2 diabetes, average HbA1c dropped from 10.9% to 7.4% over six months, a 3.5 percentage point reduction. That’s a dramatic shift, and it’s not an outlier. But keto also carries real risks for people on certain diabetes medications, and it’s not something to start without understanding what you’re getting into.
How Keto Affects Blood Sugar
When you cut carbohydrates to under 50 grams per day, your body shifts from burning glucose to burning fat for fuel. This state, called ketosis, fundamentally changes how your body handles energy. For someone with type 2 diabetes, the result is often a steep drop in blood sugar levels because there’s simply less glucose entering the bloodstream after meals.
The improvements show up quickly. In clinical trials, HbA1c (a measure of average blood sugar over two to three months) typically starts falling within the first few months. The improvements also appear to last. A two-year study of patients following a ketogenic protocol found a sustained 0.9 percentage point reduction in HbA1c along with 10% average weight loss. That level of blood sugar improvement is comparable to what some medications achieve.
Medication Reduction Is Common
One of the most compelling findings from keto research in type 2 diabetes is how often people are able to reduce or stop their medications. In one study, 60% of participants discontinued certain oral diabetes drugs, and 30% stopped metformin. None of the participants in the control group were able to do so.
A larger one-year trial found even more striking results. Among participants using insulin, 94% were able to reduce or stop it entirely. Every participant taking sulfonylureas (a class of drugs that stimulate insulin production) discontinued them. Overall diabetes medication prescriptions, excluding metformin, dropped from 57% to 30% in the keto group.
This is important context: for many people with type 2 diabetes, the appeal of keto isn’t just better numbers on a lab report. It’s the possibility of needing fewer medications and their associated side effects. That said, medication adjustments need to happen under medical supervision, because reducing insulin or drugs that lower blood sugar while changing your diet can cause dangerous drops in blood sugar if not managed carefully.
Weight Loss and Heart Health Markers
Weight loss on keto is significant but not necessarily superior to other approaches. A randomized trial comparing low-carbohydrate and low-fat diets in people with type 2 diabetes found both groups lost similar amounts of weight: about 7.6% of body weight on low-carb versus 7.1% on low-fat. Waist circumference and body fat percentage also decreased equally in both groups. So if weight loss is your primary goal, keto works, but it doesn’t have a clear edge over a well-structured low-fat diet.
Where keto does appear to stand out is in certain cholesterol markers. In a 90-day study of people with type 2 diabetes, triglycerides (a type of blood fat strongly linked to heart disease risk) dropped nearly in half, from 177 to 92 mg/dl. HDL cholesterol, often called “good cholesterol,” rose from 43 to 52 mg/dl. LDL cholesterol didn’t change significantly. Over two years, these improvements in the overall lipid profile were sustained, which is reassuring given that heart disease is the leading cause of death in people with type 2 diabetes.
The SGLT2 Inhibitor Warning
This is the single most important safety issue to understand. If you take an SGLT2 inhibitor (medications with names ending in “-flozin,” like empagliflozin or dapagliflozin), combining it with a ketogenic diet creates a real risk of a dangerous condition called euglycemic diabetic ketoacidosis. Unlike typical diabetic ketoacidosis, this version strikes when blood sugar is normal or only slightly elevated, which makes it easy to miss.
SGLT2 inhibitors work by causing your kidneys to excrete excess glucose in urine. On a very low-carb diet, this can tip the body’s acid balance to a dangerous level. Case reports have documented patients with type 2 diabetes developing this condition specifically because they combined the medication with a ketogenic diet. The 2025 American Diabetes Association standards now include specific guidance about this risk, recommending that patients on SGLT2 inhibitors know the signs of ketoacidosis and have the ability to measure their ketone levels. Some clinicians go further, advising patients to avoid keto entirely while on these drugs.
Symptoms to watch for include nausea, vomiting, abdominal pain, fatigue, and rapid breathing. If you’re on an SGLT2 inhibitor and considering keto, this is a conversation you need to have with your prescriber before making any dietary changes.
What Keto Actually Looks Like for Diabetes
The version of keto used in most diabetes research limits carbohydrates to 20 to 50 grams per day. For context, a single banana has about 27 grams of carbs, and a cup of cooked rice has around 45 grams. So this is a genuinely restrictive way of eating.
Most study protocols start at the stricter end, around 20 grams per day during an initial adaptation phase, then allow a gradual increase to 30 to 50 grams. The remaining calories come primarily from fat (roughly 60 to 80% of total intake) with moderate protein. This isn’t a high-protein diet. A typical daily breakdown used in research looks something like 130 grams of fat, 60 grams of protein, and 30 to 50 grams of carbohydrates, totaling around 1,500 calories.
The first one to two weeks are often the hardest. Many people experience fatigue, headaches, and irritability as the body adapts to burning fat instead of glucose. These symptoms, sometimes called “keto flu,” generally pass. Staying hydrated and maintaining electrolyte intake (sodium, potassium, magnesium) helps.
Long-Term Sustainability
Sticking with keto over months and years is the biggest practical challenge. In the most comprehensive long-term study available, 194 out of 262 participants in the keto group completed two years of follow-up. That’s a 74% retention rate, which is actually better than many dietary interventions, though it still means one in four people dropped out. Those who stayed showed sustained improvements in weight, blood sugar, and cholesterol markers.
Some people find that strict keto becomes easier over time as cravings for carbohydrate-rich foods diminish. Others find the social and practical limitations (eating out, family meals, food preparation) wear them down. A less rigid variation called the Modified Atkins diet, which starts at 10 to 15 grams of carbs per day and relaxes to 20 grams, offers a slightly more flexible option that still promotes ketosis.
Kidney Health Considerations
Because type 2 diabetes is one of the leading causes of kidney disease, the effect of keto on kidney function matters. Studies lasting 3 to 12 months have not shown keto harming kidney function, which is reassuring in the short term. But these studies had significant dropout rates and limited follow-up, so they can’t prove long-term safety.
There are theoretical reasons for concern with longer use. The ketogenic diet increases the body’s acid load from fatty acid breakdown, and for people who already have some degree of kidney disease, untreated metabolic acidosis (excess acid in the blood) has been linked to faster decline in kidney function. Many popular versions of keto also emphasize animal proteins and high-fat dairy, which are associated with higher levels of albumin in the urine, an early sign of kidney stress. If you have any degree of kidney disease alongside your diabetes, close monitoring of kidney function is essential while following a ketogenic diet.
Where the ADA Stands
The American Diabetes Association does not specifically endorse or reject ketogenic diets for type 2 diabetes. Its 2025 standards emphasize the quality of food sources regardless of how many carbohydrates you eat, focusing on nutrient-dense, high-fiber, minimally processed foods with healthy fats. In practice, this means the ADA considers low-carb and keto approaches acceptable as long as the food choices within that framework are sound. A keto diet built around avocados, nuts, olive oil, fish, and non-starchy vegetables is very different from one built around bacon and butter, even if the carb counts are identical.