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.

References
RCT's

1. Stern L, Iqbal N, Seshadri P, et al. The effects of low-carbohydrate versus conventional weight loss diets in
severely obese adults: one-year follow-up of a randomized trial.  Intern Med 2004 May 18;140(10):778-85. doi:
10.7326/0003-4819-140-10-200405180-00007.


2. Daly ME, Paisey R, Paisey R, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2
diabetes—a randomized controlled trial. Diabetes Medicine 2006;23(1):15-20


3. Westman EC, Yancy WS, Mavropoulos J, et al. The effect of a low-carbohydrate, ketogenic diet versus a low-
glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr Metab (Lond) 2008 Dec 19;5:36. doi:
10.1186/1743-7075-5-36.


4. Davis NJ, Tomuta N, Schechter C, et al. Comparative study of the effects of a 1-year dietary intervention of a low-
carbohydrate diet versus a low-fat diet on weight and glycemic control in type 2 diabetes. Diabetes Care 2009
Jul;32(7):1147-52. doi: 10.2337/dc08-2108. Epub 2009 Apr 14.


5. Iqbal N, Vetter ML, Moore RH, et al. Effects of a low-intensity intervention that prescribed a low-carbohydrate vs.
a low-fat diet in obese, diabetic participants. Obesity (Silver Spring) 2010;18(9):1733-80
https://doi.org/10.1038/oby.2009.460


6. Guldbrand H, Dizdar B, Bunjaku B, et al. In type 2 diabetes, randomisation to advice to follow a low-carbohydrate
diet transiently improves glycaemic control compared with advice to follow a low-fat diet producing a similar
weight loss. Diabetologia 2012;55(8):2118-27 https://doi.org/10.1007/s00125-012-2567-4


7. Tay J, Luscombe-Marsh ND, Thompson CH, et al. A very low-carbohydrate, low-saturated fat diet for type 2 diabetes management: a randomized trial. Diabetes Care. 2014;37(11):2909-2918. doi:10.2337/dc14-0845


8. Jonasson L, Guldbrand H, Lundberg AK, et al Advice to follow a low-carbohydrate diet has a favourable impact on
low-grade inflammation in type 2 diabetes compared with advice to follow a low-fat diet. Ann Med
2014;46(3):182-72 https://doi.org/10.3109/07853890.2014.894286


9. Tay J, Luscombe-Marsh ND, Thompson CH, et al. Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial. Am J Clin Nutr. 2015;102(4):780-790. doi:10.3945/ajcn.115.112581


10. Sato J, Kanazawa A, Makita S, et al. A randomized controlled trial of 130 g/day low-carbohydrate diet in type 2
diabetes with poor glycemic control. Clin Nutr 2017;36(4):992-1000. doi: 10.1016/j.clnu.2016.07.003. Epub 2016
Jul 18


11. Goday A, Bellido D, Sajoux I, et al. Short-term safety, tolerability and efficacy of a very low-calorie-ketogenic diet
interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus. Nutr Diabetes.
2016;6(9):e230. doi:10.1038/nutd.2016.36


12. Mayer SB, Jeffreys AS, Olsen MK, et al. Two diets with different hemoglobin A 1c and antiglycemic medication
effects despite similar weight loss in type 2 diabetes. Diabetes Obes Metab 2014; 16(1):90-3
https://dx.doi.org/10.1111%2Fdom.12191


13. Yamada Y, Uchida J, Izumi H, et al. A non-calorie-restricted low-carbohydrate diet is effective as an alternative therapy for patients with type 2 diabetes. Internal Medicine. 2014;53(1):13-19. doi:10.2169/internalmedicine.53.0861


14. Saslow LR, Kim S, Daubenmier JJ, et al. A randomized pilot trial of a moderate carbohydrate diet compared to a
very low carbohydrate diet in overweight or obese individuals with type 2 diabetes mellitus or prediabetes. PLoS
One 2014 Apr 9;9(4):e91027. https://doi.org/10.1371/journal.pone.0091027


15. Saslow LR, Mason AE, Kim S, et al. An online intervention comparing a very low-carbohydrate ketogenic diet and
lifestyle recommendations versus a plate method diet in overweight individuals with type 2 diabetes: a
randomized controlled trial.  J Med Internet Res. 2017 Feb 13;19(2):e36. doi: 10.2196/jmir.5806


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
diabetes in primary care: A randomized controlled feasibility trial. Diabetes Obes Metab 2020;22(4):512-20


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
success in type 2 diabetes outcomes. Metabolism – Clinical and Experimental. 2021;116.
doi:10.1016/j.metabol.2020.154591


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
effective glycemic control. Front. Endocrinol. 2021;12:779636. doi: 10.3389/fendo.2021.779636


22. Gram-Kampmann EM, Hansen CD,Hugger MB, et al. Effects of a 6-month, low-carbohydrate diet on glycaemic
control, body composition, and cardiovascular risk factors in patients with type 2 diabetes: An open-label
randomized controlled trial. Diabetes Obes Metab 2022;1-11.doi:10.1111/dom.14633


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
randomized clinical trial. JAMA Netw Open. 2022 Oct 3;5(10):e2238645. doi:
10.1001/jamanetworkopen.2022.38645. PMID: 36287562; PMCID: PMC9606840.


25. Saslow LR, Jones LM, Sen A, et al. Comparing very low-carbohydrate vs dash diets for overweight or obese
adults with hypertension and prediabetes or type 2 diabetes: a randomized trial. Ann Fam Med 2023
MayJun;21(3):256-263. doi: 10.1370/afm.2968. PMID: 37217318; PMCID: PMC10202504.


26. Dening J, Mohebbi M, Abbott G, et al. A web-based low carbohydrate diet intervention significantly improves
glycaemic control in adults with type 2 diabetes: results of the T2Diet Study randomised controlled trial. Nutr
Diabetes. 2023 Aug 27;13(1):12. doi: 10.1038/s41387-023-00240-8. PMID: 37633959; PMCID: PMC10460437.

Systematic reviews and meta-analyses

1. Castañeda-González LM, Gascon MB, Cruz AJ. Effects of low carbohydrate diets on weight and glycemic control
among type 2 diabetes individuals: a systemic review of RCT greater than 12 weeks. Nutr Hosp 2011;26(6):1270-
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.
doi:10.1016/j.diabres.2017.07.006 

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
adults with diabetes: a systematic review and meta-analysis. Diabetes Res Clin Pract 2018;139:239–252

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
interventions on metabolic control in people with type 2 diabetes: a systematic review including GRADE
assessments. Am J Clin Nutr 2018;108(2):300-331. doi: 10.1093/ajcn/nqy096

10. Schwingshackl, L, Chaimani, A, Hoffmann, G, et al. A network meta-analysis on the comparative efficacy of
different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus. Eur J
Epidemiol 2018;33, 157–170

11. Saslow LR, Summers C, Aikens JE, Unwin DJ. Outcomes of a digitally delivered low-carbohydrate Type 2 diabetes
self-management program: 1-year results of a single-arm longitudinal study. JMIR Diabetes. 2018 Aug 3;3(3):e12.
doi: 10.2196/diabetes.9333. PMID: 30291081; PMCID: PMC6238840.

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
overweight and with or without type 2 diabetes: a meta-analysis of randomized controlled trials. Nutrients
2020;12(7):2005. doi: 10.3390/nu12072005

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-
00142-z

17. Alarim RA, Alasmre FA, Alotaibi HA, Alshehri MA, Hussain SA. Effects of the ketogenic diet on glycemic control in
diabetic patients: meta-analysis of clinical trials. Cureus 2020; 12(10): e10796. doi:10.7759/cureus.10796

18. Goldenberg JZ, Day A, Brinkworth GD, et al. Efficacy and safety of low and very low carbohydrate diets for type 2
diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ.
2021;372:m4743. doi:10.1136/bmj.m4743

19. Nicholas AP, Soto-Mota A, Lambert H, Collins AL. Restricting carbohydrates and calories in the treatment of type 2 diabetes: a systematic review of the effectiveness of ‘low-carbohydrate’ interventions with differing energy levels. J
Nutr Sci 2021;10. doi:10.1017/jns.2021.67

20. Li S, Ding L, Xiao X. Comparing the efficacy and safety of low-carbohydrate diets with low-fat diets for type 2
diabetes mellitus patients: A systematic review and meta-analysis of randomized clinical trials. Int J Endocrinol
2021, Volume 2021 | Article ID 8521756 | https://doi.org/10.1155/2021/8521756

21. Parry Strong A, Wright-McNaughten M, Weatherall M, et al. Very low carbohydrate (ketogenic) diets in type 2
diabetes: a systematic review and meta-analysis of randomised controlled trials. Diabetes Obes Metab 2022
Dec;24(12):2431-2442. doi: 10.1111/dom.14837. 

22. Jayedi A, Zeraattalab-Motlagh, Jabbarzadeh B, et al. Dose-dependent effect of carbohydrate restriction for type 2
diabetes management: a systematic review and dose-response meta-analysis of randomized controlled trials. Am
J Clin Nutr 2022;116:40–56.

23. Apekey TA, Maynard MJ, Kittana M, Kunutsor SK. Comparison of the effectiveness of low carbohydrate versus
low fat diets, in type 2 diabetes: systematic review and meta-analysis of randomized controlled trials. Nutrients.
2022 Oct 19;14(20):4391. doi: 10.3390/nu14204391.

24. Choy KYC, Louie JCY. The effects of the ketogenic diet for the management of type 2 diabetes mellitus: A
systematic review and meta-analysis of recent studies. Diabetes Metab Syndr. 2023 Dec;17(12):102905. doi:
10.1016/j.dsx.2023.102905. Epub 2023 Nov 15. PMID: 38006799

25. Jooste BR, Kolivas D, Brukner P, Moschonis G. Effectiveness of technology-enabled, low carbohydrate dietary
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