Keto and Type 2 Diabetes: The Strongest Evidence

Type 2 diabetes is now the most common form of diabetes in the UK, affecting around 2.9 million people. The ketogenic diet has emerged as one of the most studied dietary interventions for managing blood glucose and improving metabolic health in people with type 2 diabetes. Unlike fad diets, the evidence here is substantial and grounded in peer-reviewed clinical research.

The ketogenic diet is a high-fat, very-low-carbohydrate eating pattern that shifts the body into ketosis—a metabolic state where fat becomes the primary fuel source. For people with type 2 diabetes, this shift has measurable effects on insulin sensitivity, blood glucose control, and the need for medication.

How Type 2 Diabetes Develops and Why Carbohydrate Matters

Type 2 diabetes develops when the body becomes resistant to insulin, the hormone that regulates blood glucose. Over time, the pancreas cannot produce enough insulin to overcome this resistance, and blood glucose rises. The condition is closely linked to dietary patterns, particularly the consumption of refined carbohydrates and added sugars, which cause rapid spikes in blood glucose and place constant demand on the pancreatic beta cells.

When someone with type 2 diabetes eats carbohydrates, their blood glucose rises more sharply than in people without the condition. The body responds by releasing more insulin, but the cells don’t respond effectively—a vicious cycle. By reducing carbohydrate intake dramatically, the ketogenic diet removes the primary driver of this cycle. Blood glucose no longer spikes, insulin demand falls, and the pancreas gets relief.

This is not a theoretical mechanism. It is observable in real time through blood glucose monitoring and confirmed in clinical trials. The reduction in carbohydrate intake is the active ingredient; the shift to fat and protein is the vehicle.

Blood Glucose Control: What the Trials Show

One of the earliest and most rigorous studies came from Yancy and colleagues in 2005. They enrolled 28 people with type 2 diabetes on a ketogenic diet and compared them to a control group on a standard low-carbohydrate diet. After 16 weeks, the ketogenic group showed a mean HbA1c reduction of 1.6 percentage points—a clinically significant drop that reflects improved average blood glucose over three months. Five participants were able to discontinue diabetes medication entirely.

A decade later, Westman and colleagues (2008) conducted a head-to-head trial comparing a ketogenic diet to a low-glycaemic index diet in people with type 2 diabetes. The ketogenic group achieved superior HbA1c reductions and required fewer medications. The low-glycaemic index group, whilst showing improvement, did not match the ketogenic results.

These are not outliers. A 2013 meta-analysis by Bueno and colleagues, published in the British Journal of Nutrition, examined 13 randomised controlled trials comparing very-low-carbohydrate ketogenic diets to low-fat diets for long-term weight loss. The analysis found that ketogenic diets produced greater weight loss and more favourable changes in triglycerides and HDL cholesterol—both important markers in type 2 diabetes management.

What matters most: people with type 2 diabetes on a ketogenic diet typically see improvements in blood glucose control within days to weeks, not months. This rapid response is one reason the approach is so compelling to both patients and clinicians.

Insulin Resistance and Metabolic Syndrome

Insulin resistance is the root cause of type 2 diabetes, and it often occurs alongside other metabolic problems—high blood pressure, abnormal cholesterol, excess abdominal fat, and elevated triglycerides. This cluster is called metabolic syndrome, and it significantly raises the risk of heart disease.

Hyde and colleagues (2019) published a study in JCI Insight examining the effect of carbohydrate restriction on metabolic syndrome independent of weight loss. This is crucial: they wanted to know whether the benefit came purely from losing weight or from the diet itself. They found that carbohydrate restriction improved metabolic syndrome markers—including fasting insulin, triglycerides, and blood pressure—even when weight loss was minimal. The mechanism is direct: lower carbohydrate intake means lower insulin demand, which allows insulin-resistant cells to become more sensitive to the hormone again.

Volek and colleagues (2008) compared carbohydrate restriction to low-fat dieting in people with metabolic syndrome. The carbohydrate-restricted group showed more favourable changes in nearly every marker: triglycerides fell further, HDL cholesterol rose more, and insulin levels dropped more sharply. This suggests that for people with insulin resistance, the type of calorie reduction matters—not all calories are equal in the context of metabolic dysfunction.

Real-World Remission: The Virta Study

One of the most ambitious recent trials is the Virta Health study, led by Hallberg and colleagues. In 2018, they published results from a one-year study of 262 people with type 2 diabetes using a ketogenic diet combined with remote coaching and monitoring. The results were striking: 60% of participants achieved remission of type 2 diabetes, defined as an HbA1c below 5.7% without diabetes medication. Among those who started on insulin, 94% were able to reduce or eliminate insulin therapy.

Following up in 2019, Athinarayanan and colleagues reported the two-year outcomes of the same cohort. Remission was sustained in 54% of participants. Weight loss averaged 10 kg, but importantly, the improvements in blood glucose control persisted even in those who regained some weight. Again, this points to a direct metabolic effect, not simply weight loss.

For context, remission rates of this magnitude are rarely seen with other dietary or pharmacological interventions. Standard diabetes care—medication adjustment, general dietary advice, and exercise—typically achieves HbA1c reductions of 0.5 to 1 percentage point. The ketogenic approach is substantially more effective in this population.

What This Means in Practice

If you live in the UK and have been diagnosed with type 2 diabetes, the evidence suggests that a ketogenic diet is worth discussing with your GP or diabetes nurse. The NHS does not currently recommend ketogenic diets as a first-line treatment, but many diabetes specialists now recognise the approach as legitimate, particularly for people who have not responded well to standard dietary advice or who wish to reduce medication.

Practically, this means focusing your meals around protein and fat sources readily available in UK supermarkets. A typical breakfast might be eggs with full-fat Greek yoghurt and berries. Lunch could be grilled salmon with olive oil and leafy greens. Dinner might be beef mince with courgettes and butter. A pack of free-range eggs at Tesco costs around £1.80 for six, whilst 500 g of Scottish salmon fillet runs approximately £5.20. Double cream at Sainsbury’s is roughly £1.50 for 300 ml.

The key is consistency. Blood glucose improvements typically appear within one to two weeks, but the full metabolic benefit—improved insulin sensitivity, stable energy, reduced hunger—takes four to eight weeks. During this period, if you are on diabetes medication, your blood glucose may drop more than expected. This is why medical supervision is essential. Your GP may need to reduce your medication dose to prevent hypoglycaemia (low blood sugar).

Seasonal eating is also relevant. Winter months in the UK offer excellent keto-friendly vegetables: broccoli, cauliflower, Brussels sprouts, and leafy greens. Spring brings asparagus and courgettes. Summer allows for more variety in salads and grilled meats. The diet is not restrictive in terms of flavour or satisfaction; it simply requires a shift in what you prioritise on your plate.

the keto adaptation timeline describes the metabolic changes that occur as your body transitions to fat burning, which is particularly relevant for people with type 2 diabetes who may experience energy fluctuations in the first few weeks. Understanding this process can help you distinguish between normal adaptation and genuine problems requiring medical attention.

managing electrolytes on a ketogenic diet is equally important for people with type 2 diabetes, especially those taking certain medications. Diuretics and some blood pressure medications can interact with the electrolyte shifts that occur on a ketogenic diet, so this is another reason to involve your healthcare team.

Cardiovascular Health and Cholesterol Concerns

One common concern is whether a high-fat ketogenic diet raises cholesterol and increases heart disease risk. The evidence suggests the picture is more nuanced than total cholesterol alone.

Kosinski and Jornayvaz (2017) reviewed the cardiovascular effects of ketogenic diets in both animal and human studies. They found that whilst LDL cholesterol sometimes rises on a ketogenic diet, this is often accompanied by a shift toward larger, less dense LDL particles—which are considered less atherogenic (less likely to damage artery walls) than small, dense particles. Simultaneously, triglycerides typically fall sharply, and HDL cholesterol rises. For people with type 2 diabetes, who often have high triglycerides and low HDL, these changes are generally favourable.

The key is individual variation. Some people on a ketogenic diet see LDL cholesterol rise significantly, whilst others see it fall. This is why baseline and follow-up blood work is important. If you have a personal or family history of early heart disease, your GP may recommend additional monitoring or a modified approach.

Appetite, Satiety, and Weight Loss

One reason people with type 2 diabetes often lose weight on a ketogenic diet is not simply calorie restriction—it is a genuine shift in appetite regulation. Sumithran and colleagues (2013) studied appetite hormones in people following a ketogenic diet. They found that ketosis is associated with reduced levels of ghrelin (the hunger hormone) and increased satiety. People report feeling fuller on fewer calories, not through willpower but through a biological change in how their appetite-regulating hormones function.

This is significant because people with type 2 diabetes often struggle with constant hunger and food cravings, particularly for refined carbohydrates. A ketogenic diet can break this cycle, making adherence easier and weight loss more sustainable.

Medication Adjustments and Medical Supervision

This cannot be overstated: if you take diabetes medication—particularly insulin or sulphonylureas—you must not start a ketogenic diet without medical supervision. As your blood glucose improves, your medication dose may need to be reduced to prevent hypoglycaemia.

The ideal scenario is to work with your GP or a diabetes specialist who is familiar with ketogenic diets. Some NHS trusts now offer low-carbohydrate diet support through specialist services. If your GP is unfamiliar with the approach, ask for a referral to a dietitian with experience in this area. The British Dietetic Association maintains a register of registered dietitians, many of whom now work with ketogenic and low-carbohydrate approaches.

Blood glucose monitoring is essential during the transition. If you use a continuous glucose monitor (CGM), you will see real-time data on how your body responds. If you use finger-prick testing, aim for at least four tests daily during the first two weeks: fasting, before meals, and two hours after meals.

Frequently Asked Questions

Q: Can a ketogenic diet cure type 2 diabetes?

A: No. Type 2 diabetes is a chronic condition. However, a ketogenic diet may support remission—a state where blood glucose returns to normal without medication. Remission is not the same as cure; the underlying insulin resistance remains, and blood glucose may rise again if carbohydrate intake increases. The Virta studies showed that 54% of participants sustained remission at two years, but this required ongoing adherence to the diet.

Q: How quickly will my blood glucose improve?

A: Most people see measurable improvements within 3 to 7 days. HbA1c, which reflects average blood glucose over three months, typically drops by 1 to 2 percentage points within 8 to 12 weeks. Individual variation is significant; some people respond faster than others.

Q: Will I need to stay on a ketogenic diet forever?

A: Not necessarily. Some people use a ketogenic diet to achieve remission and then transition to a lower-carbohydrate diet (not necessarily ketogenic) to maintain it. Others find they need to stay in ketosis to keep blood glucose stable. This is a conversation for you and your healthcare team based on your individual response.

Q: What if I have kidney disease or take blood pressure medication?

A: A ketogenic diet requires careful monitoring if you have kidney disease, as it is high in protein. If you take blood pressure medication or diuretics, the electrolyte shifts on a ketogenic diet may require dose adjustments. Always inform your GP before starting.

Q: Can I follow a ketogenic diet if I am on insulin?

A: Yes, but only under medical supervision. Insulin doses must be adjusted downward as blood glucose improves, or you risk dangerous hypoglycaemia. This is not a do-it-yourself modification; it requires close monitoring and professional guidance.

The Bottom Line

The evidence for a ketogenic diet in type 2 diabetes is substantial. Multiple randomised controlled trials and real-world cohort studies show that very-low-carbohydrate ketogenic diets produce rapid improvements in blood glucose control, often enabling medication reduction or remission. The mechanism is clear: by removing the primary driver of blood glucose spikes—carbohydrate—the diet reduces insulin demand and allows insulin sensitivity to improve.

This is not a cure, and it is not suitable for everyone. People on insulin or certain other medications must have medical supervision. But for many people with type 2 diabetes in the UK, a ketogenic diet represents one of the most effective dietary approaches available. The strongest evidence comes not from marketing claims but from peer-reviewed clinical trials, many conducted over years, showing sustained benefits.

If you are considering this approach, start by discussing it with your GP. If you decide to proceed, the Keto Dieting app tracks macronutrients and ketone levels automatically, helping you stay consistent without constant manual calculation on Google Play and the App Store.

References

1. Yancy WS, Foy M, Chalecki AM, Vernon MC, Westman EC (2005). A low-carbohydrate, ketogenic diet to treat type 2 diabetes. Nutrition & Metabolism. https://doi.org/10.1186/1743-7075-2-34
2. Westman EC, Yancy WS, Mavropoulos JC, Marquart M, McDuffie JR (2008). The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & Metabolism. https://doi.org/10.1186/1743-7075-5-36
3. Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition. https://doi.org/10.1017/S0007114513000548
4. Hyde PN, Sapper TN, Crabtree CD, et al. (2019). Dietary carbohydrate restriction improves metabolic syndrome independent of weight loss. JCI Insight. https://doi.org/10.1172/jci.insight.128308
5. Volek JS, Phinney SD, Forsythe CE, et al. (2008). Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids. https://doi.org/10.1007/s11745-008-3274-2
6. Hallberg SJ, McKenzie AL, Williams PT, et al. (2018). Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study. Diabetes Therapy. https://doi.org/10.1007/s13300-018-0373-9
7. Athinarayanan SJ, Adams RN, Hallberg SJ, et al. (2019). Long-Term Effects of a Novel Continuous Remote Care Intervention Including Nutritional Ketosis for the Management of Type 2 Diabetes: A 2-Year Non-randomized Clinical Trial. Frontiers in Endocrinology. https://doi.org/10.3389/fendo.2019.00348
8. Kosinski C, Jornayvaz FR (2017). Effects of Ketogenic Diets on Cardiovascular Risk Factors: Evidence from Animal and Human Studies. Nutrients. https://doi.org/10.3390/nu9050517
9. Sumithran P, Prendergast LA, Delbridge E, et al. (2013). Ketosis and appetite-mediating nutrients and hormones after weight loss. European Journal of Clinical Nutrition. https://doi.org/10.1038/ejcn.2013.90