Could Substituting Carbs with Healthy Fats Help Prevent Diabetes?

Replacing carbohydrates with saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) can help control and prevent type 2 diabetes, according to a new study.

Previous evidence of the effects of dietary fats and carbohydrates on the regulation of glucose and insulin was controversial, which caused confusion about dietary guidelines. This is the first study to quantify the effects of dietary fat and carbohydrates on various markers of type 2 diabetes.

Unsaturated vs Saturated Fats: How Do Specific Dietary Fats Affect Mortality?
Polyunsaturated Fat Slows Development of Diabetes

To conduct their study, the researchers searched online databases for randomized, controlled feeding trials that examined how macronutrient intake affected glucose, insulin, HbA1c, insulin sensitivity, and insulin secretion and were published by November 26, 2015.

The researchers included 102 trials composed of 239 diet arms and 4220 adults aged 18 years and older.

After a multiple-treatment meta-regression analysis, the researchers found that replacing 5% of energy from carbohydrates:

  • with SFA lowered fasting insulin;
  • with MUFA lowered HbA1c, 2-hour post-challenge insulin, and homeostasis model assessment for insulin resistance (HOMA-IR); and
  • with PUFA significantly lowered glucose, HbA1c, and fasting insulin.

Further, replacing SFA with PUFA significantly lowered glucose, HbA1c, C-peptide, and HOMA.

“This meta-analysis of randomized controlled feeding trials provides evidence that dietary macronutrients have diverse effects on glucose-insulin homeostasis,” the researchers concluded.

“In comparison to carbohydrate, SFA, or MUFA, most consistent favorable effects were seen with PUFA, which was linked to improved glycaemia, insulin resistance, and insulin secretion capacity.”

—Amanda Balbi


Imamura F, Micha R, Wu JHY, et al. Effects of saturated fat, polyunsaturated fat, monounsaturated fat, and carbohydrate on glucose-insulin homeostasis: a systematic review and meta-analysis of randomised controlled feeding trials [published online July 19, 2016]. PLoS Med.