A ketogenic diet can meaningfully improve blood sugar control for people with Type 2 diabetes, at least in the short term. It lowers fasting glucose, reduces the need for diabetes medications, and improves how your muscles respond to insulin. But the picture gets more complicated over time, and the answer depends heavily on which type of diabetes you have, what medications you take, and whether you have kidney complications.
How Keto Affects Blood Sugar
When you eat very few carbohydrates (typically under 20 to 50 grams per day), your body shifts from burning glucose to burning fat and producing ketone bodies for fuel. This shift directly reduces the amount of glucose circulating in your blood, which in turn lowers the amount of insulin your body needs to produce. Since chronically high insulin levels can themselves worsen insulin resistance, this creates a helpful feedback loop: less glucose coming in means less insulin needed, which means your cells become more responsive to insulin again.
A randomized controlled trial published in the journal Diabetes found that just three weeks on a ketogenic diet increased insulin-stimulated glucose disposal in skeletal muscle, meaning participants’ muscles became significantly better at pulling sugar out of the blood when insulin was present. The diet also reduced the liver’s baseline glucose production, likely because the body had adapted to using ketones as its primary fuel and simply needed less glucose overall.
Short-Term Benefits Are Strong
The American Diabetes Association’s 2024 Standards of Care acknowledges that low-carbohydrate and very-low-carbohydrate eating patterns reduce A1C and the need for blood sugar medications in people with Type 2 diabetes. Reviews of clinical trials confirm that carbohydrate-restricted diets (getting less than 26% of calories from carbs) are effective at lowering A1C in the first six months.
The medication reductions can be dramatic. In a study tracked by Indiana University researchers, about 60% of participants using insulin were able to stop it entirely while following a ketogenic diet. That’s a life-changing shift for someone who has been injecting insulin daily.
The Gains Fade After a Year
Here’s where the enthusiasm needs a reality check. A systematic review and meta-analysis of recent studies found that the ketogenic diet showed no significant difference in blood sugar control or weight loss compared to other diets in Type 2 diabetes patients when measured over two years. The early advantages in A1C reduction tend to narrow as time goes on, with less difference between eating patterns beyond the one-year mark.
This doesn’t mean keto “stops working.” It likely reflects the difficulty of maintaining strict carbohydrate restriction long term. Most people gradually reintroduce more carbs, and the metabolic benefits diminish accordingly. The ADA itself notes that there is no one-size-fits-all eating pattern for diabetes, and the best diet is one you can actually sustain. If keto feels manageable for you and your blood sugar improves, that’s valuable. If you find it impossible to maintain, a moderately low-carb approach may deliver similar long-term results with less friction.
Cholesterol: A Mixed Bag
Because keto is a high-fat diet, its effects on heart health markers matter, especially for people with diabetes who already face elevated cardiovascular risk. The research here is genuinely inconsistent. Some studies show improvements: lower triglycerides, higher HDL (the protective cholesterol), and reduced fasting insulin. A six-week trial in men found exactly that pattern, with no change in LDL.
But studies lasting 6 to 12 months or longer tell a different story. Some report significant increases in total cholesterol, LDL, and even triglycerides. The ADA’s 2024 guidelines note that questions remain about the long-term cardiovascular effects of very-low-carbohydrate eating patterns. If you go keto with diabetes, regular lipid panels are worth paying attention to. A diet that improves your blood sugar but worsens your heart disease risk may not be a net win.
Keto With Type 1 Diabetes
For Type 1 diabetes, the potential benefits are real but the risks are higher. An observational study of 11 people with Type 1 diabetes following a ketogenic diet found a mean A1C of 5.3% with minimal blood sugar swings. One case study documented a person who followed keto for 10 years, achieving a 43% reduction in daily insulin and an A1C of 5.5%.
The downsides, though, are significant. In that same 11-person study, lipid levels climbed above recommended thresholds and hypoglycemia (dangerously low blood sugar) increased in most participants. The fundamental problem is that people with Type 1 diabetes produce little or no insulin, so the line between nutritional ketosis and ketoacidosis, a medical emergency, is thinner. While the ketone levels observed in studies stayed below the dangerous threshold of 3.0 mmol/L, participants reported decreased exercise endurance, fatigue, and intermittent nausea.
The ADA does not recommend very-low-carbohydrate eating patterns as a routine intervention for Type 1 diabetes, and the clinical literature consistently emphasizes that it should only be attempted under close medical supervision.
Who Should Avoid Keto
Two groups need particular caution. The first is anyone taking SGLT2 inhibitors, a common class of diabetes medication. These drugs independently increase the risk of ketoacidosis, and combining them with a ketogenic diet compounds that risk. New Zealand’s medicines safety authority lists ketogenic and low-carb diets as a specific risk factor for ketoacidosis in people on SGLT2 inhibitors. If you take one of these medications, you need to discuss dietary changes with your prescriber before cutting carbs drastically.
The second group is people with kidney disease, which is common among long-term diabetics. Short-term studies (3 to 12 months) haven’t shown direct kidney damage from keto, but these studies had high dropout rates and limited follow-up, making them hard to draw firm conclusions from. The more concrete concern is metabolic acidosis. Ketogenic diets naturally produce more acid in the body, and healthy kidneys handle this without trouble. But kidneys already impaired by diabetes have a reduced ability to excrete that acid. Untreated metabolic acidosis has been shown to accelerate kidney function decline. For people with existing kidney disease, the theoretical risks outweigh the benefits when other dietary approaches, like plant-focused eating patterns, carry less potential for harm.
The ADA also advises against very-low-carb diets for people who are pregnant or lactating, children, and anyone with or at risk for disordered eating.
Making It Work Practically
If you have Type 2 diabetes and healthy kidneys, a ketogenic diet can be a powerful tool for improving blood sugar control, particularly in the first several months. The key practical considerations are medication adjustment and monitoring. Dropping your carbohydrate intake sharply while continuing the same dose of insulin or other glucose-lowering medications can cause dangerous hypoglycemia. Your medication doses will likely need to be reduced, sometimes significantly, as your blood sugar improves.
Blood pressure also tends to drop on keto, so blood pressure medications may need adjustment too. Regular blood work to track cholesterol changes is important, since the cardiovascular effects vary widely from person to person. Some people see their lipid profiles improve; others see them worsen substantially.
The ADA’s recommendation is straightforward: consider reducing overall carbohydrate intake to improve blood sugar, applied to whatever eating pattern meets your individual needs and preferences. For some people, that means strict keto. For others, a moderately low-carb approach delivers most of the benefit with better long-term adherence. The best version of this diet is the one that keeps your blood sugar stable, your lipids in check, and your kidneys safe, and that you can realistically follow for years rather than weeks.