A five week long study was conducted to determine the effect of a non-ketogenic but still low-ish carb diet on blood sugar numbers in diabetes (Diabetes 2004 Sep; 53(9): 2375-2382. Effect of a High-Protein, Low-Carbohydrate Diet on Blood Glucose Control in People With Type 2 Diabetes. Mary C. Gannon and Frank Q. Nuttall).
The study compared diets with two different macros. The carbohydrate:protein:fat ratio of the Low Carb diet was 55:15:30. The test diet ratio was 20:30:50. Again, note this was not ketogenic levels of carbohydrates. The diet was “weight-maintaining”. Assuming this is a 2000 calories a day diet that would be 2000 * 0.2 = 400 calories or 100 grams of carbohydrates a day.
The subjects were tested and their Plasma and urinary β-hydroxybutyrate were similar on both diets indicating that the lower carb group was not in nutritional ketosis.
The results were favorable for the Low Carb group.
The percentage of glycohemoglobin (HbA1c) was 9.8 ± 0.5 on the control diet and 7.6 ± 0.3 on the Low Carb diet. It was still decreasing at the end of the Low Carb diet. Thus, the final calculated glycohemoglobin was estimated to be ∼6.3–5.4%.
The reason they estimated the final HbA1c numbers would be lower was that:
The mean 24-h integrated serum glucose at the end of the control and LoBAG diets was 198 and 126 mg/dl, respectively.
Carbohydrate Control is the Key to Blood Sugar Control
As the study noted:
Data obtained in our laboratory (1–3) as well as from others (reviewed in 4) indicate that glucose that is absorbed after the digestion of glucose-containing foods (carbohyrates) is largely responsible for the rise in the circulating glucose concentration after ingestion of mixed meals. Dietary proteins, fats, and absorbed fructose and galactose resulting from the digestion of sucrose and lactose, respectively, have little effect on blood glucose concentration.
The study did increase protein by 2x but a previous study had isolated the protein affects on HbA1c:
We previously reported that a diet in which the protein content was increased from 15 to 30% of total food energy, with a corresponding decrease in carbohydrate content, resulted in a moderate but highly statistically significant mean decrease in glycohemoglobin (8.1–7.3%) after 5 weeks on the diet. This was the consequence of smaller postmeal glucose increases. The fasting glucose concentration was unchanged (12).
Thus, the increase in Protein did help the HbA1C due to the decrease in carbohydrates that came along with that increase.
The conclusion was unavoidable given the data:
Thus, the dietary modification that we refer to as the LoBAG diet has the potential for normalizing or nearly normalizing the blood glucose in people with mild to moderately severe type 2 diabetes.
Not as well as the ketogenic diet, but pretty good nevertheless. I did low carb some time back and get my HbA1C to 6.4 (with other meds). But I like my 5.2 number better now.