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Why Suggest A Low Carb Diet for Your Patients?

Feb 9, 2019
Editor: Steve Freed, R.PH., CDE

Author: Annahita Forghan, Pharm.D. Candidate 2019, LECOM College of Pharmacy

People with diabetes can benefit from a lower portion of carbohydrates in their diet, but this adjustment may lead to other risks.

Nutrition is a diabetes intervention that is considered part of lifestyle therapy. Before insulin was discovered, decreasing the intake of carbohydrates in the diet was the preferred treatment in people with diabetes. This dietary carbohydrate reduction is still an important part of diabetes therapy.  Eric Westman, MD, MHS, stated, “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. By reducing the carbohydrate in the diet, we have been able to taper patients off as much as 150 units of insulin per day in 8 d, with marked improvement in glycemic control and even normalization of glycemic parameters.”

After insulin and other diabetes medications were discovered, it was thought that the patients could consume a diet high in carbohydrates, under the impression that the medications would take care of the hyperglycemia. But this method has demonstrated hypoglycemic reactions, which leaves the patient susceptible to the dangers of morbidity and mortality. If a diet high in carbohydrates is not safe, what about a diet low in carbohydrates?

A low carb diet has its benefits. Decreased fat in body composition and decreased blood lipids would decrease circulating insulin that would have led to lipogenesis. Less lipogenesis lowers body weight, which is associated with less/slower diabetes progression. Blood glucose spikes are reduced both postprandial and fasting levels. Insulinemia is reduced, which allows better functioning of insulin when it is not exhausted, and hyperglycemia would be better controlled naturally. Blood pressure is lowered with less viscous blood that would lower the heart’s workload. Also, carbohydrate restriction can allow the beta cells to rest and recover from hyperglycemia, which can improve the insulin secretion function.

During a low carb diet, protein and fat portions would increase. There are greater satiating effects of protein and fat since these sources of energy would allow a patient to feel full faster and for longer with less carbohydrates in the diet. “One study found that despite no change in total body mass, an isocaloric diet comprising 30% protein, 50% fat, and 20% carbohydrate leads to an absolute reduction of HbA1c by 2% and improves fasting and postprandial blood glucose control in patients with type 2 diabetes mellitus.” A low carb diet can also reverse nonalcoholic fatty liver disease, a disease that is correlated with metabolic syndrome (which includes diabetes). Nonalcoholic fatty liver disease has been an increasing condition in the past decade, and it has been associated with modern diets.

Regarding the safety in a low carb diet, the study found that “Nutritional ketosis is safe and, more than that, it might be beneficial in some patients. The possible negative effects of low carb diets are headache, fatigue and muscle pain.” The negative effects would not outweigh the benefits of the nutritional ketosis in people with diabetes because the adverse symptoms would resolve in only a few days if they even occur.

There is less absolute energy intake in a low carb diet, even if fats and protein portions are increased. And due to an increase in fat intake (up to 50% in a low carb diet), there is a higher risk of death; therefore, compared to a higher lipid intake, a higher carbohydrate diet would have less risk. “The intake of 50-55% of energy from carbohydrates was associated with the lowest risk of mortality,” says the study’s authors. But with the dietary habits in the past five decades, obesity, type 2 diabetes mellitus, and cardiovascular disease have not decreased. As a result, a higher carbohydrate intake is not the solution either. Future studies should be done on different diet variations of patients’ necessary macronutrient intake and their impact on the patients’ diabetes. For example, maybe an even higher proportion of protein in the patient’s diet can substitute for a high ratio of lipids and carbohydrates.

Practice Pearls:

  • A low carb diet may be important in people with diabetes, despite their diabetes medications, as hypoglycemia poses a great mortality risk.
  • A diet with a higher portion of lipids is not the solution either when more lipids have previously demonstrated a higher risk of mortality than a diet high in carbohydrates.
  • Appropriate diet interventions are still needed in addition to medications and changes in lifestyle for people with diabetes. Further research may explore more fitting macronutrient ratios in the diet of a patient with diabetes.


Feinman RD, Pogozelski WK, Astrup A et al. Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base. Nutrition 31: 1-13, 2015. https://www.sciencedirect.com/science/article/pii/S0899900714003323. 7 January 2019.

Sima, Alexandra. “Low Carb Diet – To Love or to Hate?” Romanian Journal of Diabetes Nutrition & Metabolic Diseases. Vol. 25 / no. 3 / 2018. https://content.sciendo.com/view/journals/rjdnmd/25/3/article-p233.xml. 7 January 2019.

Vernon, M.C.; Westman, E.C.  “Has carbohydrate-restriction been forgotten as a treatment for diabetes mellitus? A perspective on the ACCORD study design.” Nutrition & Metabolism (Lond), 5 (2008), p. 10. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-5-10. 7 January 2019.

Annahita Forghan, Pharm.D. Candidate 2019, LECOM College of Pharmacy