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Very Low Carbohydrate, Low Saturated Fat Diet for Type 2 Diabetes Management

In the 24-week study, improved HbA1c and cholesterol reduced the need for medications…

 

Type 2 diabetes patients are often advised to make dietary decisions that are high in carbohydrates and low in fat and protein. Increased carbohydrates lead to high postprandial glucose readings. Due to this, there is interest in diets that are low in carbohydrates with higher amounts of fat and protein for type 2 diabetes management. Previous studies have shown that both kinds of diets (low carb and low fat) appear successful in lowering body weight, blood pressure and insulin concentrations. These previous studies have largely ignored the role of physical activity and glycemic variability.

The purpose of this study was to compare the use of a high carbohydrate, low fat diet (53% carbohydrate, 17% protein and 30% fat) to a very low carbohydrate, high unsaturated fat diet (14% carbohydrate, 28% protein and 58% fat) for their impact on glycemic control and risk factors associated with cardiovascular disease in type 2 diabetes patients. A total of 115 obese, type 2 diabetes patients were randomly assigned to one of the diet groups. In addition, they both participated in a supervised exercise program. The primary outcome was a change in HbA1c. Secondary outcomes included effects on glycemic variability, and changes in anti-glycemic medications, lipid profile and blood pressure. Measurements were taken at baseline and at trial completion at week 24.

Those in the low carbohydrate diet group showed a larger decrease in HbA1c when compared to the high carbohydrate diet group (-2.6 + 1.0% vs -1.9 + 1.2%, P= 0.002). They also experienced an increase in HDL cholesterol (0.2 + 0.3mmol/L vs 0.05 + 0.2mmol/L, P= 0.007). Changes in anti-glycemic medications were also more likely in this group as seen by the changes in the medication effects score (-0.5+ 0.5 vs -0.2 + 0.5, P= 0.003). Differences in the diets were not seen in weight loss (-12.0 +6.3kg vs 11.5 +5.5 kg, P=0.57), and no diet effect was observed in the fasting blood glucose (P=0.67), LDL reduction (P=0.81) or blood pressure (P=0.26).

The results of this study show the impact that diet selection can have on managing type 2 diabetes. While both of the diets studied in this trial showed some positive results, the very low carbohydrate diet was more effective in lowering HbA1c, reducing anti-glycemic medication requirements, and improving HDL cholesterol. Larger trials with a similar design can be used to determine if a low carbohydrate, high unsaturated fat diet continues to have an impact on managing diabetes beyond a 24-week timeframe.

Practice Pearls:

  • Type 2 diabetes patients are encouraged to make lifestyle modifications in both diet and exercise.
  • Low carbohydrate and high carbohydrate diets have both previously shown benefit in these patients, particularly in losing weight.
  • While both diets again showed improvements on weight, a very low carbohydrate, high unsaturated fat diet showed more beneficial in lowering HbA1c, anti-glycemic medication requirements and increasing HDL cholesterol.

Tay J, Luscombe-Marsh ND, Thompson CH, Noakes M, Buckley JD et al. A Very Low-Carbohydrate, Low-Saturated Fat Diet for Types 2 Diabetes Management: A Randomized Trial. Diabetes Care. Oct, 2014.