Effects of a low-carbohydrate diet in adults with type 1 diabetes: an interventional study protocol

Jessica L. Turton, Grant D. Brinkworth, Helen M. Parker, Kevin Lee, David Lim, Amy Rush, Rebecca Johnson, Kieron B. Rooney


Background: Type 1 diabetes (T1D) is an autoimmune condition characterised by pancreatic beta cell destruction and absolute insulin deficiency. The varying impact of dietary factors on blood glucose levels is well-known, yet there remains a lack of consensus surrounding the optimal dietary approaches to achieve glycaemic control in T1D. The aim of this research is to assess the efficacy of a low-carbohydrate (LC) diet in adults with T1D. We will set out to determine whether significant differences in T1D management outcomes exist between a LC diet and habitual diets higher in carbohydrate. Our primary hypothesis is that a LC diet will result in improved T1D management compared to habitual diets higher in carbohydrates.

Methods: This is a 28-week single arm within-participant intervention study involving a 4-week control period, a 12-week intervention period and a 12-week follow-up. We plan to recruit 20 adults (18-60 years) with T1D (duration ≥6 months) who have suboptimal glycaemic control (HbA1c>7.0%). The primary outcome is haemoglobin A1c (HbA1c) and secondary outcomes include glycaemic variability, frequency of hypoglycaemia, total daily insulin, and quality of life. This LC diet will start at 50 g of digestible carbohydrate per day and then there will be opportunity to increase or decrease within a broader range of 25-75 g/day according to individual blood glucose levels and personal preference.  Participants will meet individually with the study dietitian for a total of six fortnightly sessions to receive dietary instruction, strategies, and education. Participants will continue to work with a member of their usual diabetes care team for specific advice regarding insulin management.

Conclusions: Current dietary management strategies for T1D appear to be lacking in effect and additional dietary therapies, including LC diets, require urgent consideration. Therefore, an interventional study investigating a patient-led LC dietary approach will be of important clinical relevance for healthcare practitioners and may help to better inform clinical practice guidelines for T1D management.

Trial Registration: https://www.anzctr.org.au/ACTRN12621000764831.aspx


Diabetes, Glycaemic control, Low-carbohydrate diet, Diet therapy

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Craig M, Twigg S, Donaghue K. National evidence-based clinical care guidelines for type 1 diabetes in children, adolescents and adults. 2011.

Cavero-Redondo I, Peleteiro B, Álvarez-Bueno C. Glycated haemoglobin A1c as a risk factor of cardiovascular outcomes and all-cause mortality in diabetic and non-diabetic populations: a systematic review and meta-analysis. BMJ Open. 2017;7:e015949.

Kelly CT, Mansoor J, Dohm GL. Hyperinsulinemic syndrome: the metabolic syndrome is broader than you think. Surgery. 2014;156:405-11.

Wang MY, Yu X, Lee Y. Iatrogenic hyperinsulinemia in type 1 diabetes: its effect on atherogenic risk markers. J diabetes its complications. 2013;27:70-74.

McKnight JA, Wild SH, Lamb MJ. Glycaemic control of Type 1 diabetes in clinical practice early in the 21st century: an international comparison. Diabetic med j Bri Diabetic Asso. 2015;32:1036-50.

Sainsbury E, Kizirian NV, Partridge SR. Effect of dietary carbohydrate restriction on glycemic control in adults with diabetes: A systematic review and meta-analysis. Diabetes rese clin practice. 2018;139:239-52.

Snorgaard O, Poulsen GM, Andersen HK. Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes. BMJ open diabetes res care. 2017;5:e000354.

Huntriss R, Campbell M and 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 nutrition. 2018;72:311-25.

Turton J, Brinkworth GD, Field R. An evidence-based approach to developing low-carbohydrate diets for type 2 diabetes management: A systematic review of interventions and methods. Diabetes, Obesity Metabolism. 2019;21:2513-25.

Tay J, Thompson CH, Luscombe-Marsh ND. 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, obesity metabolism. 2018;20:858-71.

Diabetes Australia. Position Statement: Low carbohydrate eating for people with diabetes. Available at: https://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/dbd70857-a834-45b0-b6f1-ea2582bbe5c7.pdf. Accessed Jan 03 2019.

Diabetes UK. Position statement: Low-carb diets for people with diabetes. Available at: https://www.diabetes.org.uk/resources-s3/2017-09/low-carb-diets-position-statement-May-2017.pdf. Accessed Mar 21 2019.

Davies MJ, D’Alessio DA, Fradkin J. Management of Hyperglycemia in Type 2 Diabetes, 2018. A Consensus Report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD). Diabetes Care. 2018;41:2669.

Lawton J, Rankin D, Cooke DD. Dose Adjustment for Normal Eating: a qualitative longitudinal exploration of the food and eating practices of type 1 diabetes patients converted to flexible intensive insulin therapy in the UK. Diabetes res clin practice. 2011;91:87-93.

Buyken AE, Toeller M, Heitkamp G. Carbohydrate sources and glycaemic control in Type 1 diabetes mellitus. EURODIAB IDDM Complications Study Group. Diabetic medicine j Bri Diabetic Association. 2000;17:351-9.

Turton JL, Raab R and Rooney KB. Low-carbohydrate diets for type 1 diabetes mellitus: A systematic review. PLOS ONE. 2018;13:e0194987.

Krebs JD, Parry Strong A, Cresswell P. A randomised trial of the feasibility of a low carbohydrate diet vs standard carbohydrate counting in adults with type 1 diabetes taking body weight into account. Asia Pacific j clin nutrition. 2016;25:78-84.

Schmidt S, Christensen MB, Serifovski N. Low versus high carbohydrate diet in type 1 diabetes: A 12-week randomized open-label crossover study. Diabetes, obesity metabolism. 2019;21:1680-88.

Piłaciński S and Zozulińska-Ziółkiewicz DA. Influence of lifestyle on the course of type 1 diabetes mellitus. Arch Med Sci. 2014;10:124-34.

Tiwari S, Riazi S and Ecelbarger CA. Insulin's impact on renal sodium transport and blood pressure in health, obesity, and diabetes. Am J Physiology-Renal Physiol. 2007;293:F974-84.

Mente A, O'Donnell M, Rangarajan S, et al. Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies. Lancet (London, England). 2016;388:465-75.

Krebs JD, Arahill J, Cresswell P. The effect of additional mealtime insulin bolus using an insulin-to-protein ratio compared to usual carbohydrate counting on postprandial glucose in those with type 1 diabetes who usually follow a carbohydrate-restricted diet: A randomized cross-over trial. Diabetes, obesity metabolism. 2018;20:2486-9.

Hallberg SJ, McKenzie AL, Williams PT. Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study. Diabetes Therapy. 2018;9:583-612.

Murdoch C, Unwin D, Cavan D. Adapting diabetes medication for low carbohydrate management of type 2 diabetes: a practical guide. Br J Gen Pract. 2019;69:360-61.

Burroughs TE, Desikan R, Waterman BM. Development and Validation of the Diabetes Quality of Life Brief Clinical Inventory. Diabetes Spectrum. 2004;17:41-9.

Krebs JD, Arahill J, Cresswell P. The effect of additional mealtime insulin bolus using an insulin-to-protein ratio compared to usual carbohydrate counting on postprandial glucose in those with type 1 diabetes who usually follow a carbohydrate-restricted diet: A randomized cross-over trial. Diabetes, obesity metabolism. 2018;20:2486-9.

Wolever TMS, Chiasson J-L, Josse RG. Effects of Changing the Amount and Source of Dietary Carbohydrates on Symptoms and Dietary Satisfaction Over a 1-Year Period in Subjects with Type 2 Diabetes: Canadian Trial of Carbohydrates in Diabetes (CCD). Canadian J Diabetes. 2017;41:164-76.

Osler W, McCrae T. The Principles and Practice of Medicine: Designed for the Use of Practitioners and Students of Medicine. D. Appleton. 1921.

Turton JL, Struik NA, Riley M. Adults with and without type 1 diabetes have similar energy and macronutrient intakes: an analysis from the Australian Health Survey 2011-2013. Nutrition research (New York, NY) 2020; 84: 25-32.

Holmes-Walker DJ, Abraham MB, Chee M. Glycaemic outcomes in Australasian children and adults with Type 1 Diabetes: failure to meet targets across the age spectrum. Int med j. 2021;2021:06-19.