Dr Peter Brukner OAM

Show me the evidence: A low carb approach to managing type 2 diabetes

8 mins read

People invest significant time and money in efforts to improve their health, so examining the scientific evidence behind nutritional advice is important because it helps us seperate the hype from the truth. 

If you’re worried about the evidence behind a low carb approach, rest assured that substantial evidence supports this dietary strategy for managing type 2 diabetes.

Now, diving into the evidence, let's first look at randomised control trials (RCTs) that are related to low carb and type 2 diabetes.

Randomised control trials

There are various evidence levels in medicine and the highest levels are associated with meta-analyses and randomised control trials (RCTs) — the gold standard for scientific experiments. 

To date, 26 RCTs have compared low carb diets of less than 130g carbohydrate per day to low fat diets of less than 35% or total calories with people living with type 2 diabetes. The studies range in length from three months to two years.

In all 26 studies, the low carb diets were associated with a reduction in HbA1c, the primary
outcome measure used. In 23/26 studies, the reduction in HbA1c was greater in the low carb
versus the low fat diets, and 18/23 were statistically significant. None of the three studies in
which the low fat showed greater reduction in HbA1c were significant. 

Systematic reviews and meta-analyses

Twenty five systematic reviews/meta-analyses have looked at the relationship between low
carb diets and T2D.

The study by Jahedi et al (2022) evaluated the dose-dependent effect of carbohydrate
restriction in patients with type 2 diabetes. Fifty trials with 4291 patients were identified. At 6
months, compared with a carbohydrate intake between 55%–65% and through a maximum
reduction down to 10%, each 10% reduction in carbohydrate intake reduced HbA1c, fasting
plasma glucose and body weight. There were also reductions in total cholesterol, LDL
cholesterol, triglycerides, and systolic blood pressure (SBP). Levels of HbA1c, FPG, body
weight, TG, and SBP decreased linearly with the decrease in carbohydrate intake from 65%
to 10%.

Apekey et al (2022) reviewed twenty-two RCTs comprising 1391 mostly obese participants
with T2D. At 3 months, a LC vs. LF diet significantly reduced HbA1c levels, mean difference
(95% CI) of -0.41% (-0.62, -0.20). LC diet significantly reduced body weight, BMI, fasting
insulin and triglycerides and increased total cholesterol and HDL-C levels at the short-to-
intermediate term, with a decrease in the requirement for antiglycaemic medications at
intermediate-to-long term

Is there evidence that this type of program can be effectively delivered online?

Online programs similar to Defeat Diabetes have been established for several years in both the UK and the USA.

A recent UK study reviewed results from the Low Carb program on diabetes.co.uk which had over 400,000 participants. Of the 743 participants in the study with a starting HbA1c at or above the type 2 diabetes threshold of 6.5%, 195 (26.2%) reduced their HbA1c to below the threshold while taking no glucose-lowering medications or just metformin.

Of the participants who were taking at least one hypoglycemic medication at baseline, more than 40% reduced one or more of these medications. Almost half of all participants lost at least 5% of their body weight. Overall, glycemic control and weight loss improved, especially for participants who completed all 10 modules of the program. For example, participants with elevated baseline HbA1c who engaged with all 10 weekly modules reduced their HbA1c from 9.2% to 7.1% and lost an average of 6.9% of their body weight.

In the USA, a remote care model run by Virta Health has also proven to be successful, with approximately 50% of participants putting their diabetes into remission.

How does the evidence support the Defeat Diabetes Program?

The Defeat Diabetes program uses the latest scientific evidence in our endeavour to achieve similarly excellent results. We are conducting ongoing research into the effectiveness of our program, the results of which will be published.

Furthermore, the increasing volume of scientific evidence demonstrates the effectiveness of the low carb approach to the management of type 2 diabetes and has been acknowledged by organisations such as Diabetes Australia, the UK National Health Service and the American Diabetes Association.


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2. Daly ME, Paisey R, Paisey R, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2
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3. Westman EC, Yancy WS, Mavropoulos J, et al. The effect of a low-carbohydrate, ketogenic diet versus a low-
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5. Iqbal N, Vetter ML, Moore RH, et al. Effects of a low-intensity intervention that prescribed a low-carbohydrate vs.
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16. Tay J, Thompson CH, Luscombe-Marsh ND, et al. Effects of an energy-restricted low-carbohydrate, high unsaturated fat/low saturated fat diet versus a high-carbohydrate, low-fat diet in type 2 diabetes: A 2-year randomized clinical trial. Diabetes Obes Metab. 2018;20(4):858-871. doi:10.1111/dom.13164

17. Morris E, Aveyard P, Dyson P, et al. A food‐based, low‐energy, low‐carbohydrate diet for people with type 2
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18. Chen C-Y, Huang W-S, Chen H-C, et al. Effect of a 90 g/day low-carbohydrate diet on glycaemic control, small, dense low-density lipoprotein and carotid intima-media thickness in type 2 diabetic patients: An 18-month randomised controlled trial. PLOS ONE. 2020;15(10):e0240158. doi:10.1371/journal.pone.0240158

19. Govers E, Visscher TLS, Bouwman W, Lourens A, Schuilinga B, Otten A. Carbohydrate content of diet determines
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20. Durrer C, McKelvey S, Singer J, et al. A randomized controlled trial of pharmacist-led therapeutic carbohydrate and energy restriction in type 2 diabetes. Nat Commun 2021;12(1):5367. doi:10.1038/s41467-021-25667-4

21. Han Y, Cheng B, Guo Y, et al. A low- carbohydrate diet realizes medication withdrawal: a possible opportunity for
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22. Gram-Kampmann EM, Hansen CD,Hugger MB, et al. Effects of a 6-month, low-carbohydrate diet on glycaemic
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23. Thomsen MN, Skytte MJ, Astrup A, et al. The clinical effects of a carbohydrate-reduced high-protein diet on glycaemic variability in metformin-treated patients with type 2 diabetes mellitus: A randomised controlled study. Diabetologia. 2022 Mar;65(3):506-517. doi: 10.1007/s00125-021-05628-8.

24. Dorans KS, Bazzano LA, Qi L, et al. Effects of a low-carbohydrate dietary intervention on hemoglobin A1c: A
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Systematic reviews and meta-analyses

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6. doi: 10.1590/S0212-16112011000600013.

2. Ajala O, English P, Pinkney J. Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr 2013;97(3):505-516. doi:10.3945/ajcn.112.042457

3. Fan Y, Di H, Chen G, et al. Effects of low carbohydrate diets in individuals with type 2 diabetes: systematic review
and meta-analysis. Int J Clin Exp Med 2016;9(6):11166-11174 www.ijcem.com /ISSN:1940-5901/IJCEM0023504

4. Snorgaard O, Poulsen GM, Andersen HK, Astrup A. Systematic review and meta-analysis of dietary carbohydrate
restriction in patients with type 2 diabetes. BMJ Open Diabetes Res Care. 2017;5(1):e000354. doi:10.1136/bmjdrc-2016-000354

5. Meng Y, Bai H, Wang S, et al. Efficacy of low carbohydrate diet for type 2 diabetes mellitus management: A systematic review and meta-analysis of randomized controlled trials. Diabetes Res Clin Pract 2017;131:124-131.

6. Valenzuela Mencía J, Fernández Castillo R, Martos Cabrera MB, et al. Diets low in carbohydrates for type 2 diabetics. Systematic review. Nutr Hosp 2017;34(1):224-234. doi:10.20960/nh.999

7. Sainsbury E, Kizirian NV, Partridge SR, et al. Effect of dietary carbohydrate restriction on glycemic control in
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8. Huntriss R, Campbell M, Bedwell C. The interpretation and effect of a low-carbohydrate diet in the management of type 2 diabetes: a systematic review and meta-analysis of randomised controlled trials. Eur J Clin Nutr 2018;72(3):311-325  doi:10.1038/s41430-017-0019-4

9. van Zuuren EJ, Fedorowicz Z, Kuijpers BT, et al. Effects of low-carbohydrate- compared with low-fat-diet
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12. Turton J, Brinkworth GD, Field R, Parker H, Rooney K. An evidence‐based approach to developing low‐carbohydrate diets for type 2 diabetes management: a systematic review of interventions and methods. Diabetes Obes Metabol 2019;21(11):2513-2525. doi: 10.1111/dom.13837.

13. Korsmo-Haugen HK, Brurberg KG, Mann J, et al. Carbohydrate quantity in the dietary management of type 2
diabetes: a systematic review and meta-analysis. Diabetes Obes Metab 2019;21:15–27

14. McArdle PD, Greenfield SM, Rilstone SK, et al. Carbohydrate restriction for glycaemic control in type 2 diabetes: a
systematic review and meta-analysis. Diabet Med 2019;36:335–348

15. Choi YJ, Jeon S-M, Shin S. Impact of a ketogenic diet on metabolic parameters in patients with obesity or
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16. Yuan X, Wang J, Yang S, et al. Effect of the ketogenic diet on glycemic control, insulin resistance, and lipid metabolism in patients with T2DM: a systematic review and meta-analysis. Nutr Diabetes. 2020;10(1):1-8. doi:10.1038/s41387-020-

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