Rates of diabetes are soaring in the United States and around the world. Here, we investigate the medical literature to identify whether a ketogenic diet, which is high in fat and low in carbohydrate, can improve symptoms of diabetes.
In theory, the ketogenic diet seems to be a natural fit for people with diabetes. When blood glucose is elevated following a meal, diabetics are unable to properly remove glucose from the bloodstream via uptake by tissues. Insulin is a hormone responsible for signaling tissue cells to uptake glucose. Diabetes can be caused either by an inability to synthesize insulin (Type 1 Diabetes, T1D) or by resistance of body tissues to respond to insulin (Type 2 Diabetes, T2D). Thus, it seems that a ketogenic diet could benefit diabetics by limiting the carbohydrate intake, thereby limiting blood glucose spikes and reducing dependence on insulin. Several studies support this theory.
One study of 49 people with T2D compared a ketogenic diet to a low glycemic diet over 24 weeks. While both diets improved health status, the ketogenic diet group experienced greater benefits in hemoglobin A1C (HA1C) levels (-1.5% vs. -0.5%), an indicator of long-term blood glucose1. Impressively, 95% of patients on the ketogenic diet were able to reduce or eliminate use of diabetic medication compared to 65% in the low glycemic group. A study of 28 obese type 2 diabetics following a ketogenic diet for 16 weeks found similar benefits2. HA1C levels were reduced by 16% and 81% of patients were able to reduce or eliminate medication. It should be noted that while ketogenic dieters in both studies lost weight, reduction in body weight did not predict improvement in HA1C, indicating that the diet itself improved blood glucose levels independent of weight loss.
A longer-term study evaluated a ketogenic in obese type 2 diabetics for 56 weeks, and found that fasting blood glucose levels significantly decreased over the course of the study3. Interestingly, individuals with the highest initial fasting blood glucose had a much greater decrease than individuals with lower initial fasting blood glucose (-56% vs. -9%), suggesting that the ketogenic diet may be particularly effective for type 2 diabetics with poorly controlled blood glucose.
The beneficial effects of ketogenic diets in individuals with diabetes, particularly T2D, in both human and animal studies4,5,6,7 has prompted some clinicians to urge for low-carbohydrate diets to be the primary intervention for treatment8. Given these promising studies, diabetics may want to consult with their doctors to determine if a ketogenic or low-carbohydrate diet is right for them.
- Westman, E. C., Yancy, W. S., Mavropoulos, J. C., Marquart, M. & McDuffie, J. R. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr. Metab. (Lond). 5, 36 (2008).
- Yancy, W. S. et al. A low-carbohydrate, ketogenic diet to treat type 2 diabetes. Nutr. Metab. (Lond). 2, 34 (2005).
- Dashti, H. M. et al. Beneficial effects of ketogenic diet in obese diabetic subjects. Mol. Cell. Biochem. 302, 249–256 (2007).
- Al-Khalifa, A., Mathew, T. C., Al-Zaid, N. S., Mathew, E. & Dashti, H. M. Therapeutic role of low-carbohydrate ketogenic diet in diabetes. Nutrition 25, 1177–1185 (2009).
- Poplawski, M. M. et al. Reversal of diabetic nephropathy by a ketogenic diet. PLoS One 6, (2011).
- Okuda, T. & Morita, N. A very low carbohydrate ketogenic diet prevents the progression of hepatic steatosis caused by hyperglycemia in a juvenile obese mouse model. Nutr. Diabetes 2, e50 (2012).
- Badman, M. & Kennedy, A. A very low carbohydrate ketogenic diet improves glucose tolerance in ob/ob mice independently of weight loss. Am. J. … 2215, 1197–1204 (2009).
- Accurso, A. et al. Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome: time for a critical appraisal. Nutr Metab 5, 9 (2008).