Type 2 diabetes mellitus

Background

Unlike type 1 diabetes, which results from autoimmune destruction of insulin producing, pancreatic β-cells, type 2 diabetes mellitus (type 2 diabetes) represents approximately 90% of all cases of overall diabetes, is largely preventable with lifestyle modifications.[1]

In 2017-18, approximately 5% of Australians had type 2 diabetes, and around 1.2 million hospitalisations were attributable to the disorder.[2] It was projected that $2.1 billion in lost GDP was due to diabetes in 2015, which would increase to $2.9 billion by 2030.[3] In New Zealand, over 250,000 individuals are affected by type 2 diabetes.[4]

Socioeconomic disadvantage and living in rural or remote locations is associated with higher prevalence of the disorder in Australia.[5]

The condition

Despite the misinformation surrounding carbohydrates and blood glucose, T2DM results from resistance to insulin in target organs, caused by build up of intracellular lipids preventing proper functioning of the glucose uptake process.[6] The early stages are characterised by insulin overproduction as a compensatory measure to encourage glucose uptake in target organs.[7] Over time, pancreatic β-cell function deteriorates progressing the disease from impaired glucose tolerance to type 2 diabetes.[7]

Elevations in fasting blood glucose and glycated haemoglobin are used for diagnosis, with the magnitude of increase in concentrations used to differentiate between impaired glucose tolerance and progression to type 2 diabetes.[8]

There are significant long-term health risks associated with type 2 diabetes diagnosis, particularly where blood glucose concentrations are not well controlled.[9,10] Risks of heart attack, stroke and all cause mortality are significantly increased in diabetic patients.[10]

The cause

Increased plasma free fatty acids and intracellular lipid accumulation drive insulin resistance and ultimately the progression to type 2 diabetes.[6,11]

Nutritional considerations

Nutrition and lifestyle management is recommended as a first line therapy for newly diagnosed cases of insulin resistance and type 2 diabetes, however, this is not followed consistently in clinical practice and it is reported that only 5-10% of patients are given any opportunity to manage the condition without pharmaceutical intervention.[19]

Weight loss, irrespective of cause, can improve glucose control and insulin sensitivity.[20] Diet quality over the long-term is critical to not only the management of the condition, but also prevention of associated co-morbitities.[19] A diet high in plant-foods and dietary fibre, while low in saturated fats has been shown in epidemiological studies to be associated with reduced risk of comorbid conditions, reduced weight and better blood glucose control.[22–25]

A plant-based diet for long-term management
For patients with existing type 2 diabetes, medication requirements can be significantly reduced or in some cases, eliminated, by switching to a plant-based or predominantly plant-based diet, with abundant vegetables, whole grains and fruits.[28,29] In addition to improved glycemic control, plant-based dietary patterns also reduce the risk of complications commonly associated with type 2 diabetes such as cardiovascular disease and kidney disease.[29]

Given the long-term health benefits, The American College of Endocrinologists states that a “primarily plant-based diet” should be adopted as part of lifestyle therapy for the condition.26 The recent Position Statement from the American College of Lifestyle Medicine (ACLM), also endorsed by the The American College of Endocrinologists, outlines that a WFPB diet is the diet which ACLM member practitioners report as being most important in achieving T2D remission outcomes. [35]

ACLM T2D quote

A systematic review of the use of plant-based diets for patient wellbeing and management of type 2 diabetes found that the dietary pattern was associated with significant improvement in wellbeing, improved HbA1c, weight, lipid levels and overall health.[27]

Dietary components, such as green leafy vegetables, fruits and whole grains are associated with a reduced risk of type 2 diabetes.[14,22,30] Evidence consistently shows that those following plant-based diets have lower body mass index (BMI), reduced waist circumference and lower risk of all chronic diseases, including type 2 diabetes. [28,31–34]

Looking for evidence-based, patient friendly resources? Share our type 2 diabetes information for the general public.

Further resources

PCRM logo

Physicians Committee for Responsible Medicine: summary, 18-minute TEDx video, fact sheet download and links to related articles.

[1] Atkinson MA, Eisenbarth GS, Michels AW. Type 1 diabetes. The Lancet. 2014;383(9911):69-82. doi:10.1016/S0140-6736(13)60591-7
[2] Diabetes, How many Australians have diabetes? Australian Institute of Health and Welfare. Accessed April 6, 2021. https://www.aihw.gov.au/reports/diabetes/diabetes/contents/how-many-australians-have-diabetes
[3] Schofield D, Shrestha RN, Cunich MM, et al. The costs of diabetes among Australians aged 45–64 years from 2015 to 2030: projections of lost productive life years (PLYs), lost personal income, lost taxation revenue, extra welfare payments and lost gross domestic product from Health and WealthMOD2030. BMJ Open. 2017;7(1):e013158. doi:10.1136/bmjopen-2016-013158
[4] About diabetes. Ministry of Health NZ. Accessed June 21, 2021. https://www.health.govt.nz/our-work/diseases-and-conditions/diabetes/about-diabetes
[5] Australian Institute of Health and Welfare. Diabetes, Type 2 diabetes. Australian Institute of Health and Welfare. Accessed June 30, 2021. https://www.aihw.gov.au/reports/diabetes/diabetes-snapshot/contents/how-many-australians-have-diabetes/type-2-diabetes
[6] Krssak M, Falk Petersen K, Dresner A, et al. Intramyocellular lipid concentrations are correlated with insulin sensitivity in humans: a 1H NMR spectroscopy study. Diabetologia. 1999;42(1):113-116. doi:10.1007/s001250051123
[7] Kahn SE, Cooper ME, Del Prato S. Pathophysiology and treatment of type 2 diabetes: Perspectives on the past, present and future. Lancet. 2014;383(9922):1068-1083. doi:10.1016/S0140-6736(13)62154-6
[8] Nolan CJ, Damm P, Prentki M. Type 2 diabetes across generations: from pathophysiology to prevention and management. The Lancet. 2011;378(9786):169-181. doi:10.1016/S0140-6736(11)60614-4
[9] Cavalot F, Pagliarino A, Valle M, et al. Postprandial Blood Glucose Predicts Cardiovascular Events and All-Cause Mortality in Type 2 Diabetes in a 14-Year Follow-Up: Lessons from the San Luigi Gonzaga Diabetes Study. Diabetes Care. 2011;34(10):2237-2243. doi:10.2337/dc10-2414
[10] Norhammar A, Bodegård J, Nyström T, Thuresson M, Eriksson JW, Nathanson D. Incidence, prevalence and mortality of type 2 diabetes requiring glucose-lowering treatment, and associated risks of cardiovascular complications: a nationwide study in Sweden, 2006–2013. Diabetologia. 2016;59(8):1692-1701. doi:10.1007/s00125-016-3971-y
[11] Boden G. Free fatty acids-the link between obesity and insulin resistance. Endocr Pract Off J Am Coll Endocrinol Am Assoc Clin Endocrinol. 2001;7(1):44-51. doi:10.4158/EP.7.1.44
[14] DeFronzo RA, Ferrannini E, Groop L, et al. Type 2 diabetes mellitus. Nat Rev Dis Primer. 2015;1(1):1-22. doi:10.1038/nrdp.2015.19
[19] Forouhi NG, Misra A, Mohan V, Taylor R, Yancy W. Dietary and nutritional approaches for prevention and management of type 2 diabetes. BMJ. 2018;361:k2234. doi:10.1136/bmj.k2234
[20] Lean MEJ, Leslie WS, Barnes AC, et al. Durability of a primary care-led weight-management intervention for remission of type 2 diabetes: 2-year results of the DiRECT open-label, cluster-randomised trial. Lancet Diabetes Endocrinol. 2019;7(5):344-355. doi:10.1016/S2213-8587(19)30068-3
[21] Di Rosa C, Lattanzi G, Taylor SF, Manfrini S, Khazrai YM. Very low calorie ketogenic diets in overweight and obesity treatment: Effects on anthropometric parameters, body composition, satiety, lipid profile and microbiota. Obes Res Clin Pract. 2020;14(6):491-503. doi:10.1016/j.orcp.2020.08.009
[22] Reynolds AN, Akerman AP, Mann J. Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses. PLOS Med. 2020;17(3):e1003053. doi:10.1371/journal.pmed.1003053
[23] Bozzetto L, Costabile G, Della Pepa G, et al. Dietary Fibre as a Unifying Remedy for the Whole Spectrum of Obesity-Associated Cardiovascular Risk. Nutrients. 2018;10(7):943. doi:10.3390/nu10070943
[24] InterAct Consortium. Dietary fibre and incidence of type 2 diabetes in eight European countries: the EPIC-InterAct Study and a meta-analysis of prospective studies. Diabetologia. 2015;58(7):1394-1408. doi:10.1007/s00125-015-3585-9
[25] Lie L, Brown L, Forrester TE, et al. The Association of Dietary Fiber Intake with Cardiometabolic Risk in Four Countries across the Epidemiologic Transition. Nutrients. 2018;10(5):628. doi:10.3390/nu10050628
[26] Garber AJ, Abrahamson MJ, Barzilay JI, et al. Consensus Statement by the American Association of Clinical Endocrinologists and American College of Endocrinology on the Comprehensive Type 2 Diabetes Management Algorithm – 2018 Executive Summary. Endocr Pract Off J Am Coll Endocrinol Am Assoc Clin Endocrinol. 2018;24(1):91-120. doi:10.4158/CS-2017-0153
[27] Toumpanakis A, Turnbull T, Alba-Barba I. Effectiveness of plant-based diets in promoting well-being in the management of type 2 diabetes: a systematic review. BMJ Open Diabetes Res Care. 2018;6(1):e000534. doi:10.1136/bmjdrc-2018-000534
[28] Wright N, Wilson L, Smith M, Duncan B, McHugh P. The BROAD study: A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes. Nutr Diabetes. 2017;7(3):e256-e256. doi:10.1038/nutd.2017.3
[29] McMacken M, Shah S. A plant-based diet for the prevention and treatment of type 2 diabetes. J Geriatr Cardiol JGC. 2017;14(5):342-354. doi:10.11909/j.issn.1671-5411.2017.05.009
[30] Bondonno NP, Davey RJ, Murray K, et al. Associations between fruit intake and risk of diabetes in the AusDiab cohort. J Clin Endocrinol Metab. Published online June 2, 2021:dgab335. doi:10.1210/clinem/dgab335
[31] Turner-McGrievy G, Mandes T, Crimarco A. A plant-based diet for overweight and obesity prevention and treatment. J Geriatr Cardiol JGC. 2017;14(5):369-374. doi:10.11909/j.issn.1671-5411.2017.05.002
[32] Tonstad S, Butler T, Yan R, Fraser GE. Type of vegetarian diet, body weight, and prevalence of type 2 diabetes. Diabetes Care. 2009;32(5):791-796. doi:10.2337/dc08-1886
[33] Barnard ND, Katcher HI, Jenkins DJ, Cohen J, Turner-McGrievy G. Vegetarian and vegan diets in type 2 diabetes management. Nutr Rev. 2009;67(5):255-263. doi:10.1111/j.1753-4887.2009.00198.x
[34] Barnard ND, Alwarith J, Rembert E, et al. A Mediterranean Diet and Low-Fat Vegan Diet to Improve Body Weight and Cardiometabolic Risk Factors: A Randomized, Cross-over Trial. J Am Coll Nutr. 2021;0(0):1-13. doi:10.1080/07315724.2020.1869625
[35] Kelly J, Karlsen M, Steinke G. Type 2 Diabetes Remission and Lifestyle Medicine: A Position Statement From the American College of Lifestyle Medicine. Am J Lifestyle Med. 2020;14(4):406-419. Published 2020 Jun 8. doi:10.1177/1559827620930962

Return to menu of health conditions.