For a long time, benefits of ketogenic diet have been explored. From epilepsy, cancer, and Alzheimer’s to metabolic disorders like obesity and PCOS, it has served as an invaluable tool in treatment of many medical conditions. Type 2 diabetes mellitus (T2DM) is no exception; the use of ketogenic diet is already widespread and popular among those with diabetes. Here, we review how ketogenic diet can be of value to the management of type 2 diabetes. 

An Overview of Type 2 Diabetes
Type 2 diabetes mellitus (T2DM) is a condition characterized by a chronic high blood glucose level. It is marked by high levels of insulin in the blood, insulin resistance, and/or defective pancreatic B-cell function. T2DM is also often accompanied by decreased immune function, inflammation, and changes in the microbiome. Microvascular and macrovascular complications might develop secondary to high blood glucose and insulin resistance.

Type 2 Diabetes and Obesity
Both genetic and environmental factors are responsible for development and progression of type 2 diabetes. Indeed, diagnosis of T2DM is on the rise as global epidemic of obesity increases. This correlates to sedentary lifestyles and high-calorie diets becoming increasingly accessible and prevalent. The trend is projected to continue to rise in the coming years. In fact, it is reported that approximately 60% of type 2 diabetes patients are obese (BMI  30 kg/m2). Abdominal obesity (visceral fat), independent of BMI, is itself a risk factor for T2DM. 

Insulin resistance (IR) is one of the main reasons for high blood glucose (hyperglycemia). IR refers to a state when the cells of tissues do not properly respond to hormone insulin. This leaves glucose to accumulate in the bloodstream because it is unable to get into the cells. 

It is thought that obesity has much to do with insulin resistance, and vice versa. A study from 2018 suggests that insulin resistance promotes fat accumulation that is characteristic of T2DM. Another study suggests that lipid accumulation in the muscles and the liver induces insulin resistance. Because of this closely intertwined relationship, weight loss is all the more important when it comes to management of T2DM.

An Overview of Ketogenic Diet (KD)
There are many diet options for weight loss, including low- to very low-calorie diets, and high protein diets. Ketogenic diet (KD) is a high-fat, low-carb dietary intervention that is intended to promote breakdown of fats. The main goal of ketogenic diet is to achieve ketosis, which involves using fatty acids in the form of ketone bodies to use as the body’s main source of fuel. This simulates the body’s physiological state when it is fasting. Ketogenic diet follows the following proportion of macromolecule consumption (macros): 5% carbohydrates (20-50 g/day), 20-25% proteins, 70-75% fat. The goal is to aggressively cut down carbohydrate intake and to limit protein consumption (Protein can be turned into glucose when it is consumed in excess). When the body has minimal glucose, it will turn to fatty acids to burn as energy.

How Ketogenic Diet is Beneficial to Type 2 Diabetes
The main goal of diabetes treatment is to achieve glycemic control and to prevent or minimize development of secondary complications. Management of lipid profiles and blood pressure are also important. Diabetic remission is possible with the appropriate lifestyle changes, accommodated by medications or therapies that help with increased insulin activity and sensitivity. A meta-analysis from 2020 summarized 13 studies and their results of how ketogenic diet (KD) affects T2DM. The follow-up week after the KD intervention for each study varied from 1 to 56 weeks. 

The meta-analysis revealed significant improvements in both carbohydrate and lipid metabolism after KD intervention. It showed decreases in both fasting blood glucose and HbA1c, a hemoglobin that binds to sugars in the bloodstream. HbA1c is a marker that shows blood glucose control within the past 2-3 months. It is also known to be a good indicator of possible microvascular complications secondary to T2DM. Triglyceride, LDL, and total cholesterol were decreased, as well. On the other hand, HDL, also known as the “good” cholesterol, was increased.

HOMA-IR, a test that estimates the amount of insulin needed for blood glucose control, reflected trends of improvement in insulin resistance after KD intervention. This could be due to a combination of factors, including reduced carbohydrates and loss of fat. Diabetic patients also showed significant reductions in weight, waist circumference, and BMI. Both diastolic and systolic blood pressure decreased. It was also shown that type 2 diabetic patients with severe obesity experienced greater benefits (better lipid profiles, blood glucose readings) from weight loss. And although this was not tested, the authors expected that along with these improvements will also come alleviation of clinical symptoms associated with T2DM. These symptoms may include insomnia, chills, itching, and limb numbness among many others.

An Endnote
Overall, ketogenic diet promises plenty of benefits for people with type 2 diabetes, especially for those who are also obese. It even allows a sustainable change in lifestyle because of the satiety it offers. However, debates regarding the long-term effects of high fat consumption is still ongoing. Because of this, a balanced diet (e.g. choosing unsaturated fats vs saturated fats) within the given macros is recommended for those who pursue this diet. Blood ketone levels should also be checked daily to ensure that the body is in the right state of ketosis.

It is advised that any dietary intervention for medical purposes are discussed with medical providers.