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Achieving stable long-term blood sugar, glycated hemoglobin (HbA1c), below 7.0% or 53mmol/mol has been the top priority in diabetes therapy for years. This corresponds to an actual average blood sugar of 147 mg/dl or 8.2mmol/L. These values were defined in this way because they have been shown to reduce the risk of long-term consequences.

Change in HbA1c

In a review of over 300,000 diabetics by Turton, Raab and Rooney (2018), it was found that 84% of the participants did not reach the target value of 7% HbA1C. In their work, Turton, Raab and Rooney examined whether a reduced intake of carbohydrates (KH) (= low-carb diet) could improve long-term blood sugar.

The American Diabetes Association (ADA) defines "low carb" as meaning that the daily intake of total energy is covered with a maximum of 130 g of carbohydrates or 26% with carbohydrates. Buyken et al. (2000) were able to show that reducing carbohydrates can lead to improved blood sugar control. Because fewer carbohydrates are taken in, insulin has to be injected less often from the outside and the risk of a diabetic misjudging the administration of insulin is reduced. As a result, less strong fluctuations and less severe high and low blood sugar levels are to be expected.

In the end, nine studies were evaluated. Of these, three studies were able to demonstrate a significant reduction in HbA1c levels. The remaining studies showed a trend towards lowering the HbA1c value. However, the change was not large enough to be classified as “significant”.

Change in insulin requirements

The daily amount of insulin administered was also measured in each case. Two studies were also able to show significant reductions in the amount per day (U/d). One group changed the daily amount from 41.1 ± 3.5 to 35.3 ± 4.1 U/d, the second group even from 66.4 ± 25.3 to 44.2 ± 16.5 U/d. In the other studies, too, less insulin was required in the low-carb group. However, a value that would be considered statistically significant was not reached here either. For diabetics, however, every reduction in artificial insulin and, above all, in HbA1c is worth striving for.

As a conclusion from this review, it can be said that a low-carb diet can have a positive effect on the HbA1c value and reduce insulin requirements.


  • Turton JL, Raab R, Rooney KB (2018) Low-carbohydrate diets for type 1 diabetes mellitus: A systematic review. PLoS ONE 13(3): e0194987.

  • Buyken AE, Toeller M, Heitkamp G, Irsigler K, Holler C, Santeusanio F, et al. Carbohydrate sources and glycemic control in type 1 diabetes mellitus. EURODIAB IDDM Complications Study Group. Diabetes Med. 2000; 17(5):351-9. PMID: 10872533

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