How Does the Keto Diet Affect Insulin and Blood Glucose?

Risa Groux, CN
 | Published: 
October 19, 2020

“The ketogenic diet is a powerful tool to treat T2D. For many patients, it is absolutely life-changing. It needs specialized training to use it effectively and safely. It is not uncommon to see the need of hundreds of units of insulin evaporate in days or weeks.”  (Michael Mindrum, MD 4/19/2019)

You’ve probably heard the buzz about the ketogenic diet among the general public and medical professionals alike, and for good reason. A large and growing body of research supports the use of this very low carbohydrate, high fat diet to address many health concerns, such as type 2 diabetes, neurological and neurodegenerative disorders, metabolic syndrome, and difficult-to-treat issues, such as lymphatic and migraine disorders. In this article, we’ll take a close look at select mechanisms of the ketogenic diet that underlie its efficacy in some of these situations.

Carbohydrate restriction has demonstrated efficacy for improving glycemic control in type 2 diabetes and metabolic syndrome. In fact, it is so powerful that a team of researchers active in this field have said it should be the first approach in diabetes management, and presented significant evidence to support their case. Because type 2 diabetes is a condition defined by high blood sugar, it is obvious that minimizing foods that increase blood sugar should be a foundational aspect of disease management:

At the end of our clinic day, we go home thinking, ‘The clinical improvements are so large and obvious, why don't other doctors understand?’ Carbohydrate restriction is easily grasped by patients: Because carbohydrates in the diet raise the blood glucose, and as diabetes is defined by high blood glucose, it makes sense to lower the carbohydrate in the diet.  (Eric Westman, MD)

This was understood as far back as 1877:

There are few diseases which present to the practitioner so clear an indication of what is to be done [...] a Diabetic should exclude all saccharine [sugary] and farinaceous [starchy] materials from his diet.” (William Morgan, MD, Diabetes Mellitus: Its History, Chemistry, Anatomy, Pathology, Physiology and Treatment)

Significant reduction in carbohydrate intake has a quick and powerful effect on reducing blood glucose, to the point that individuals with T2D may need to decrease or even altogether discontinue insulin injections on the first day of beginning a keto diet:

With the ketogenic diet, there may be asmuch as a 50–100 mg/dL reduction in blood glucose on the first day of eliminating foods containing starch or sugar. We have seen individuals on very high doses of insulin (hundreds of units of insulin) no longer need insulin on the first day of eliminating carbohydrates from the diet. (Westmanet al., 2018)

This statement confirms results from a 2017 study examining the feasibility and effects of a ketogenic diet for type 2 diabetes. In addition to substantial reductions in HbA1c, diabetes medications were discontinued or reduced in a significant proportion of subjects. (Patients should always work with their physician to make any adjustments to their medications and not do so on their own.)

Not only do keto diets lower blood glucose; but they also lower insulin levels, which is a crucial component of the disease. Because type 2 diabetes is diagnosed only through measuring glucose, many people with a wide array of health issues caused by chronic hyperinsulinemia but who are normoglycemic are given an inaccurate sense of security regarding their metabolic health. Some of the many conditions either primarily caused by hyperinsulinemia or exacerbated by it, regardless of whether blood glucose is elevated, include PCOS, erectile dysfunction, hypertension, gout, skin tags, benign prostatic hyperplasia (BPH), and more.

The lowering of insulin levels may explain the improvements in HDL, triglycerides, and LDL particle size observed in clinical trials of ketogenic diets, as well as the lowering of uric acid levels and reduction in gout attack frequency in subjects following reduced carbohydrate protocols. (Elevated insulin impairs renal uric acid excretion as well as sodium excretion, which may contribute to the connection between elevated insulin and hypertension.) Keto diets have also demonstrated improvement of non-alcoholic fatty liver disease(NAFLD), resulting in “rapid and dramatic reductions of liver fat” in subjects with obesity and NAFLD. Insulin resistance may be a significant factor in the pathophysiology of liver fat accumulation, so an intervention that decreases insulin levels may improve NAFLD.

I cannot emphasize enough that chronically elevated insulin levels is a major contributor to a wide range of health issues, affecting almost every tissue system even in people with normal blood glucose. This understanding led one researcher to call the lowering of insulin levels “the sleeping giant in patient care.” While minimizing carbohydrate intake through a low carb or keto diet is not the only way to correct chronic hyperglycemia and hyperinsulinemia, it is definitely one of the most effective.

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