FACT SHEET:
Type 2 Diabetes Mellitus & Diet
How to prevent and treat T2DM with nutrition

Diabetes Mellitus
Key points
  • Diabetes currently affects approximately 463 million people worldwide, and the number is projected to rise to 700 million people by 2045—that is 10.9% of the world’s population (1).
  • Type 2 diabetes mellitus (T2DM) accounts for up to 90% of all diabetes cases (1).
  • An unfavorable dietary composition and increased visceral adipose tissue are reversible and among the key risk factors for T2DM (1).
  • T2DM itself increases the risk of atherosclerosis, neuropathy, and diabetic foot syndrome, as well as nephropathy and retinopathy, a leading cause of visual impairment blindness (1).
  • Insulin resistance may occur decades before T2DM becomes diagnostically apparent, so early preventive dietary strategies are of paramount importance.

In 2019 an estimated 4.2 million deaths were attributable to diabetes and its complications (1).

Pathomechanisms That Are Influenced by Diet:

Adipose Tissue Dysfunction

Overnutrition

Diets high in fat, simple sugars, and processed foods are calorically dense and facilitate energy surplus and adipose tissue (AT) dysfunction resulting in:

  • downregulated secretion of insulin-sensitizing adiponectin (2, 3)
  • chronic tissue inflammation due to macrophage infiltration (2, 4)
  • release of proinflammatory cytokines causing impaired insulin signaling and lipolysis (2, 3, 4, 5)
  • upregulated lipolysis leading to release of free fatty acids (FFAs) (2, 4)

Glucotoxicity

Rapidly Absorbable Carbohydrates

cause increased insulin needs (increasingly difficult to meet in lipotoxic state)

can induce de novo lipogenesis leading to increased accumulation of AT

contribute to chronically elevated blood glucose levels resulting in glucotoxicity(3, 6)

  • production of advanced glycation end products (AGEs), which cause
    glomerulosclerosis and thus contribute to diabetic nephropathy
  • increased oxidative stress and apoptosis of β-cells

Lipotoxicity

Dietary Fat

dietary saturated fat contributes to oversupply of saturated FFAs (7, 8, 9)

  • saturated FFAs cause IR through mitochondrial dysfunction,
    increased oxidative stress, and proinflammatory signaling (7, 10)

on the contrary, monounsaturated and omega-3 polyunsaturated fatty acids increase insulin sensitivity (7, 8, 9)

Ectopic Fat

FFAs from adipocytes and dietary saturated fat are redirected to and accumulated at multiple anatomic sites as ectopic fat (EF) (2, 4)

EF causes lipotoxicity,25 which contributes to organ dysfunction and IR, thus resulting in both impaired insulin secretion and increased insulin needs (3, 4)

  • liver
    – upregulated gluconeogenesis and glycogenolysis (3)
  • skeletal muscle
    – build-up of intramyocellular lipid, which interferes with GLUT4 translocation (4, 6, 7)
    –  decreased uptake of blood glucose and glycogen synthesis (3, 4)
  • Pancreas
    – increased oxidative stress and lipoapoptosis of β-cells (3, 6, 8)

Glucolipotoxicity

lipotoxic and glucotoxic effects cause progressive β-cell dysfunction and death, which leads to the inability to compensate for increased insulin needs resulting
in the hallmark of T2DM: hyperglycemia

The Scientific Evidence

Epidemiological Evidence

  • significant association between abdominal obesity and incidence of T2DM (11, 12)

  • 74% reduced risk of developing diabetes by long-term adherence to a vegetarian diet vs. meat-containing diet (13)

  • significant inverse association between higher adherence to a plant-based dietary pattern and risk of T2DM (14)

Evidence from RCTs and Corresponding Meta-Analyses

  • significant decrease in HbA1c when following a low-carbohydrate diet, low glycemic index (GI) diet or Mediterranean diet compared to control diets (15)

  • 7.4% reduction in HbA1c levels on low GI-diets compared to high-GI diets (16)

  • vegan, vegetarian, and Mediterranean diets show greater reduction in bodyweight and HbA1c levels, delayed requirement for diabetes medication, and improved glycemic control compared to other diets (17)

General Recommendations

Eat predominantly or entirely from a wide variety of whole plant foods:

  • Maximize the intake of high-quality plant foods such as vegetables, whole grains, legumes, fruits, nuts, seeds, herbs, and spices; your health will benefit from every step towards more whole plant foods.
  • Eliminate or limit all processed foods, refined carbohydrates, and sugar-sweetened foods and beverages.
  • Eliminate or limit red and processed meat products (such as burgers, sausages, bacon, ham, salami, dried meat, canned meat, and pastrami).
  • Eliminate or limit other animal products such as poultry, fish, eggs, cheese, and dairy.
  • Make sure to cover potentially critical nutrients with a wide variety of plant foods, enriched foods/drinks, or supplements (especially vitamin B12 and vitamin D); find more information in our Nutrition Library.

Disease-Specific Recommendations

  • Eliminate chronic excessive calorie intake. This is best achieved by choosing plant foods with low calorie density such as green vegetables, starchy root vegetables, legumes, and fruit with lower sugar content such as berries and citrus fruits.

  • Aim for optimal body weight, which is best achieved by consuming predominately whole plant foods—losing weight helps keeping blood sugar levels under control.

  • When eating carbohydrates, choose low glycemic food options such as fruits, vegetables, legumes, minimally processed whole grains, and nuts. Those will help control blood sugar levels and also promote
    weight loss.

  • Limit saturated fats, from both animal and plant sources as much as possible (18, 19), and replace them with monounsaturated and omega-3 polyunsaturated fats from nuts and seeds or high-quality carbohydrates such as whole grains, as this has been shown to ameliorate IR (7, 18). 

  • Make it a habit to eat beans, chickpeas, lentils, and split peas, as pulses help keep blood sugar levels stable.

  • Regularly include inulin-rich foods such as chicory root and Jerusalem artichoke. Inulin is an indigestible kind of fiber, which may help maintain steady blood sugar levels (20), ameliorate IR (21), and reduce LDL cholesterol (22).

  • Regularly season your food with the spice turmeric as one of its active compounds curcumin has been shown to improve glycemic control (23, 24).

For more details on how to implement a whole food, plant-based diet, have a look at our brochure.

HIDE
Sources
(1) International Diabetes Federation. IDF Diabetes Atlas, 9th edn. Brussels, Belgium: 2019. Available at: https://www.diabetesatlas.org
 
(2) Nolan, C.J., P. Damm, and M. Prentki, Type 2 diabetes across generations: from pathophysiology to prevention and management. Lancet, 2011. 378(9786): p. 169-81.
 
(3) Cornell S. Continual evolution of type 2 diabetes: an update on pathophysiology and emerging treatment options. TCRM. April 2015;621.
 
(4) Snel M, Jonker JT, Schoones J, Lamb H, de Roos A, Pijl H, et al. Ectopic Fat and Insulin Resistance: Pathophysiology and Effect of Diet and Lifestyle Interventions. International Journal of Endocrinology. 2012; 2012:1–18.
 
(5) Ni, Y., et al., Adipose Tissue Macrophage Phenotypes and Characteristics: The Key to Insulin Resistance in Obesity and Metabolic Disorders. Obesity (Silver Spring), 2020. 28(2): p. 225-234.
 
(6) Tesauro M, Mazzotta FA. Pathophysiology of diabetes. In: Transplantation, Bioengineering, and Regeneration of the Endocrine Pancreas. Elsevier; 2020. p. 37–47. 
 
(7) Rachek LI. Free Fatty Acids and Skeletal Muscle Insulin Resistance. In: Progress in Molecular Biology and Translational Science. Elsevier; 2014.p. 267–92. 
 
(8) Engin AB. What Is Lipotoxicity? In: Engin AB, Engin A, editors. Obesity and Lipotoxicity. Cham: Springer International Publishing; 2017. p. 197–220. (Advances in Experimental Medicine and Biology; vol. 960).
 
(9) Lepretti M, Martucciello S, Burgos Aceves M, Putti R, Lionetti L. Omega-3 Fatty Acids and Insulin Resistance: Focus on the Regulation of Mitochondria and Endoplasmic Reticulum Stress. Nutrients. 2018 Mar 14;10(3):350.
 
(10) Savage DB, Watson L, Carr K, Adams C, Brage S, Chatterjee KK, u. a. Accumulation of saturated intramyocellular lipid is associated with insulin resistance. J Lipid Res. 2019 Jul;60(7):1323–32.
 
(11) WHO (‎2016)‎. Global report on diabetes. https://apps.who.int/iris/handle/10665/204871. Accessed 22 Jan 2020. ISBN 9789241565257
 
(12) Freemantle, N., et al., How strong is the association between abdominal obesity and the incidence of type 2 diabetes? Int J Clin Pract, 2008. 62(9): p. 1391-6.
 
(13) Barnard, N.D., et al., Vegetarian and vegan diets in type 2 diabetes management. Nutr Rev, 2009. 67(5): p. 255-63.
 
(14) Qian, F., et al., Association Between Plant-Based Dietary Patterns and Risk of Type 2 Diabetes: A Systematic Review and Meta-analysis. JAMA Intern Med, 2019.
 
(15) Ajala, O., P. English, and J. Pinkney, Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr, 2013. 97(3): p. 505-16.
 
(16) Brand-Miller J, Hayne S, Petocz P, Colagiuri S. Low-Glycemic Index Diets in the Management of Diabetes: A meta-analysis of randomized controlled trials. Diabetes Care. 2003 Aug 1;26(8):2261–7.
 
(17) Papamichou, D., D.B. Panagiotakos, and C. Itsiopoulos, Dietary patterns and management of type 2 diabetes: A systematic review of randomised clinical trials. Nutr Metab Cardiovasc Dis, 2019. 29(6): p. 531-543.
 
(18) Luukkonen PK, Sädevirta S, Zhou Y, Kayser B, Ali A, Ahonen L, u. a. Saturated Fat Is More Metabolically Harmful for the Human Liver Than Unsaturated Fat or Simple Sugars. Dia Care. 2018 Aug;41(8):1732–9.
 
(19) Hernández EÁ, Kahl S, Seelig A, Begovatz P, Irmler M, Kupriyanova Y, u. a. Acute dietary fat intake initiates alterations in energy metabolism and insulin resistance. Journal of Clinical Investigation. 2017 Jan 23;127(2):695–708.
 
(20) Wang L, Yang H, Huang H, Zhang C, Zuo H-X, Xu P, u. a. Inulin-type fructans supplementation improves glycemic control for the prediabetes and type 2 diabetes populations: results from a GRADE-assessed systematic review and dose–response meta-analysis of 33 randomized controlled trials. J Transl Med. 2019 Dec;17(1):410.
 
(21) Rao M, Gao C, Xu L, Jiang L, Zhu J, Chen G, et al. Effect of Inulin-Type Carbohydrates on Insulin Resistance in Patients with Type 2 Diabetes and Obesity: A Systematic Review and Meta-Analysis. Journal of Diabetes Research. 2019 Aug 27; 2019:1–13.
 
(22) Liu F, Prabhakar M, Ju J, Long H, Zhou H-W. Effect of inulin-type fructans on blood lipid profile and glucose level: a systematic review and meta-analysis of randomized controlled trials. Eur J Clin Nutr. 2017 Jan;71(1):9–20.
 
(23) Poolsup N, Suksomboon N, Kurnianta PDM, Deawjaroen K. Effects of curcumin on glycemic control and lipid profile in prediabetes and type 2 diabetes mellitus: A systematic review and meta-analysis. Atkin SL, editor. PLoS ONE. 2019 Apr 23;14(4):e0215840.
 
(24) Pivari F, Mingione A, Brasacchio C, Soldati L. Curcumin and Type 2 Diabetes Mellitus: Prevention and Treatment. Nutrients. 2019 Aug 8;11(8):1837.