November 14, 2019
LAS VEGAS — Adults with type 2 diabetes can experience multiple diabetes-specific benefits beyond weight loss by undertaking a low-carbohydrate diet, although potential risks must be addressed, according to a speaker at ObesityWeek.
“Carbohydrate restriction is a viable option for patients with type 2 diabetes,” Jeff Stanley, MD, medical director and practicing physician at Virta Health in San Francisco, said during a presentation. “Nutritional ketosis can support diabetes reversal or significant improvements in diabetes by reducing insulin resistance while also providing alternate fuel to glucose.”
Low-carb benefits
According to Stanley, low-carb diets are now among the standard of care dietary recommendations in numerous guidelines, including those from the American Diabetes Association and the European Association for the Study of Diabetes. These eating plans generally fall into one of two approaches. The first is the very low-carb, or ketogenic, diet that requires less than 10% of daily caloric intake to come via carbohydrates, which equates to roughly 50 g or less. The second is the more conventional low-carb diet that requires 25% or less of daily caloric intake to come via carbohydrates, equating to between 51 g and 130 g of carbohydrates. According to Stanley, that 25% or lower mark is the sweet spot for what constitutes a low-carb diet.
There is a sizeable body of research that points to the many benefits of a low-carb diet, including for individuals with type 2 diabetes. According to Stanley, randomized controlled trials are the primary method in which these diets have been evaluated, and the body of literature outpaces that for plant-based diets, the Mediterranean diet and Dietary Approaches to Stop Hypertension (DASH) diet. Evidence from much of this research has shown some considerable benefits. Weight loss is primary among these, but for those with type 2 diabetes, Stanley also noted that a low-carb diet may help lower HbA1c, glycemic excursions, insulin resistance, liver enzymes associated with nonalcoholic fatty liver disease, the need for insulin or diabetes medications, and cardiovascular risk while simultaneously increasing insulin sensitivity. In fact, based on findings from the aptly named Indiana Diabetes Reversal Study, diabetes can be reversed for many patients. Even if this endpoint is not met, the benefits are still numerous.
“It’s important to note that there are people who either they’ve been on insulin too long or they’re very sick or their HbA1c is very high,” Stanley said. “They’re not necessarily going to strive for that subdiabetic HbA1c, but we think we can still help by bringing those levels down and, importantly, getting them on less meds.”
Caution required
There are still issues to weigh when recommending that a patient with type 2 diabetes start a low-carb diet. According to Stanley, one of the most important factors to consider is the diet’s effects on lipids. Although the evidence is unclear, Stanley noted that there is a potential for LDL cholesterol to follow an upward trajectory with this dietary pattern.
“It may have more to do with, potentially, the amount of saturated fat in the diet, patient adherence or other factors that we’re not aware of, but it is certainly something to be cognizant of,” Stanley said. “Be careful with patients with genetic lipid disorders like familial hyperlipidemia and also in folks with lipoprotein lipase deficiency. The key here is that if someone is starting this diet, it is worthwhile tracking their lipids and seeing what the response is, and then intervening as needed.”
Diabetic ketoacidosis is another potential negative effect from low-carb diets. Stanley noted that nutritional ketosis is possible with low-carb diets, especially the ketogenic diet, but that this is not the same as diabetic ketoacidosis. According to Stanley, maintaining a range of 0.5 mmol/L to 3 mmol/L in blood beta-hydroxybutyrate equates to this nutritional ketosis, whereas much higher levels lead to diabetic ketoacidosis. The risk for this condition is higher for those who take SGLT2 inhibitors.
“SGLT2 inhibitors actually induce a low level of ketosis in patients, and in combination with carbohydrate restriction, that can cause the level to go too high,” Stanley said. “A lot of the guidelines recommend either caution or just saying that patients who are taking these should not do a ketogenic diet or they should stop the medication before starting.”
Beyond physiologic factors, physicians must consider that not every patient will be able to follow these types of diets perfectly.
“There’s no clear difference between adherence to a low carbohydrate approach vs. others — they’re all hard,” Stanley said. “What we need to do is work to support patients better to stick with whatever they try.”
In addition, Stanley said despite the current research available, more is needed, especially with assessments for longer-term outcomes. This holds true for more than just low-carb diets.
“I am not disparaging the other types of approaches. There is solid evidence for all of these approaches, and the most important thing when we are looking at such an epidemic of diabetes and obesity that we need to give patients options,” Stanley said. “This doesn’t mean that low carbohydrate is the answer for everybody. It means that certain patients will do well with this, and we should offer it to them as an option.” – by Phil Neuffer
Reference:
Stanley J. The power of low carb nutrition for diabetes treatment. Presented at: ObesityWeek 2019; Nov. 3-7, 2019; Las Vegas.
Disclosure: Stanley reports he is an employee and shareholder in Virta Health.