June 7, 2023

Managing Type 1 Diabetes With a Very Low-Carb, Eucaloric Diet

A 1-year, real-life retrospective experience
Switching from a high-carb diet to a low-carb one improved patients’ control of their diabetes.


Kleiner A, Cum B, Pisciotta, L, et al. Safety and efficacy of eucaloric very low-carb diet (EVLCD) in type 1 diabetes: a one-year real life retrospective experience. Nutrients. 2022;14(15):3208.

Study Objective

To see if changing patients with type 1 diabetes mellitus (T1DM) from a high-carb/low-fat diet to a eucaloric, low-carb, high-fat, moderate-protein diet would affect their diabetes control, use of insulin, or lipids

Key Takeaway

This retrospective case study showed that a eucaloric, low-carb diet significantly lowered the hemoglobin A1C, the use of insulin, and low-density lipoprotein (LDL) levels in type 1 diabetic patients without causing untoward effects.  


Retrospective case series of T1DM patients seen at a single clinic


The study included 33 T1DM patients on insulin therapy; 23 were female. The average age was 41.6 years, and the average time with diabetes was around 14.3 years. The publication did not list exclusion criteria. 


The participants voluntarily switched from a high-carbohydrate (>200 g/d; 55% of calories), low-fat (20% of calories) diet to a low-carbohydrate (<50 g/d; 5% of calories), high-fat (70% of calories), eucaloric diet. There was no difference in the percentage of calories from protein between the diets (25%). The intervention was 1-year in duration. 

Study Parameters Assessed

The study parameters included before (baseline) and after (1 year): hemoglobin A1C, body mass index (BMI), total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, creatinine, liver enzymes (aspartate aminotransferase [AST] and alanine transaminase [ALT]), and insulinemia. 

Participants performed a home assessment of glucose and ketonemia before and after every meal and recorded the amount of insulin used. Researchers collected glycemia data weekly from the patients.

Primary Outcome

There was no predetermined primary outcome in this retrospective, observational study. The authors noted, “Our aim is to evaluate the glycemic control, the amount of insulin needed in order to maintain glycemic control and safety of EVLCD.”

Key Findings

Glycemic control:

A1C: The percentage of patients with A1c values less than 7% was 12.1% at baseline and 57.6% after 1 year (P<0.01). Overall, 32/33 patients saw improvements in glycemia control through a lowering of A1C

Insulin usage:

The average dosage of rapid-acting insulin decreased significantly from 18.3 IU (±9.5 IU) per day to 10.3 IU (±6.5 IU) per day (P<0.001). This dramatic reduction led to a statistically significant reduction in the total insulin used from 36.7 IU (±14.9 IU) per day to 28.9 IU (±9.1 IU) per day (P<0.001). 

Adverse events:

At baseline 54.5% of patients reported at least 1 episode of level 2 hypoglycemia in the past year, and 30.3% reported a severe hypoglycemia event in the past year. At study conclusion, 24.2% of patients reported a single episode of level 2 hypoglycemia while maintaining the EVLCD in the prior year (P<0.001).


This study occurred in hospitals in Italy, in clinics run by the main author, Kleiner. The authors declared no conflict of interest. 

Practice Implications & Limitations

This was an intriguing study showing that when T1DM patients changed from a high-carb to low-carb diet, their diabetes was better controlled. Specifically, they needed to use significantly less rapid-acting insulin—from 18.3 IU to 10.3 IU on average—and their basal insulin stayed the same; their LDL levels reduced significantly (98.5 to 84.4 mg/dL; P=0.005); BMI was stable; and blood pressure was stable. There was a statistically significant decrease in episodes of serious hypoglycemia from before to after. No side effects or negative reactions occurred due to the study. 

The study was small, but the results were good, statistically significant, and encouraging. Another limitation was the voluntary change of diet, showing extra-motivated adult patients. The clinical staff closely followed the patients as well, and such close oversight may have improved the results.

The diet itself was limited—veggies, olive oil, fish, white meat, eggs, nuts, butter, and cheese.

The diet itself was limited—veggies, olive oil, fish, white meat, eggs, nuts, butter, and cheese. Oddly, to add variety, the diet also contained low-carb food products—bread, pasta, rice, rusks, and sweets—all with a carb content lower than 5%. They did not give further information on those products to help us understand what they were made of to ensure low carbs. 

I am personally not surprised by this study as I have been using a low-carb diet with all diabetic patients for 30 years, since I read Richard Bernstein, MD’s book and preceptored with him. Bernstein originated the idea of using a low-carb diet with diabetic patients since, as a type 1 diabetic patient himself, his health and glucose control magnificently improved when he did so. It is good to see more studies proving the logic, lucidity, viability, safety, and efficacy of diabetic patients eating a low-carb diet. One can only hope that someday in the future, conventional physicians will have this enormously powerful lightbulb go on as well.

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