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Food & Diabetes

The “western diet” is an unhealthy consequence of modern life, and includes a high content of refined carbohydrates such as white rice, sugary beverages, white bread, and processed foods. The more you consume of these foods and drinks, and the less you “move”, the greater stress you place on your beta cells and increase your risk of developing type 2 diabetes. These foods raise your blood glucose levels quickly, causing a surge in insulin from your beta cells, and with time, this leads to insulin resistance and beta cell exhaustion (insulin depletion).

How do different foods compare in their ability to raise blood glucose levels?

Glycemic index

The glycemic index (GI) of a food is an indication of whether the carbohydrate content raises blood glucose levels quickly, moderately or slowly. Different carbohydrates are digested and absorbed at different rates, and the higher the G.I value of a food, the higher and more quickly blood glucose levels increase following ingestion.

Foods are ranked on the GI scale from 1 to 100, with 100 being the GI value of pure glucose. Carbohydrates which are slowly absorbed such as wholegrain bread or brown rice, and vegetables, have a low GI rating (typically < 55) while refined carbohydrates such as white rice, sugary beverages and cakes will have a much higher G.I value.

In addition to individual foods and their different GI values, the overall GI of what you are eating will be affected by the combination of foods or drink. For example, combining bananas with yoghurt will lead to a lower overall GI than consuming bananas alone. It is important to remember that the amount of carbohydrate consumed will often have a bigger effect on blood glucose levels than the GI value, so the quantity, as well as the quality of carbohydrate consumption, is also very important.

Glycemic load (GL) is another measure of how foods and drinks raise our blood sugar levels. Unlike the GI, GL does take the amount of carbohydrate into consideration. It is calculated by the following equation:

GL = GI x available CHO in a 100g serving / 100. (CHO=carbohydrate)

Some risky foods for diabetes

Foods with a high GI such as refined starch, sugary beverages and potatoes increase the risk of diabetes while those with a low GI such as cold breakfast cereal and yoghurt reduce the risk of developing type 2 diabetes (1).

Consuming high GI carbohydrates while also eating low amounts of cereal fiber also predisposes to a higher risk of diabetes (2, 3).

Fiber from cereal correlates with a lower risk of developing type 2 diabetes, and this is thought to be due to the minerals and micronutrients present in these foods such as magnesium.

Potatoes act like refined carbohydrate, and eating one serving of potato instead of one serving of wholegrain food can lead to a 30% increased risk of developing diabetes (4).

Furthermore, a study in Asia, where levels of white rice consumption are high, found that increasing white rice consumption from 200g or less to 300g per day increased the risk of developing type 2 diabetes by 60% (5).

Thus consuming refined carbohydrates such as white bread, white rice and pasta, and sugary beverages, markedly increases the chances of developing type 2 diabetes.

Why are refined carbohydrates so hazardous to health?

Refined grains, which include foods where the wholegrain has been removed and refined, also have most of the nutrients removed; they have a high GI and are rapidly absorbed, creating a spike in blood glucose. This, in turn, leads to a corresponding increase in insulin being released from the beta cells. This greater demand of insulin over several years leads to insulin resistance and beta cell exhaustion, leading eventually to type 2 diabetes.

Trans-fats, such as those in processed foods are also implicated in the development of type 2 diabetes (6).

Studies have found that sugary beverages play a role in increasing type 2 diabetes risk; drinking one or more sugary beverages per day increases risk by 40% (7, 8).

Red meat, and particularly processed meat, also increases the risk of diabetes, so needs to be consumed in moderation (9). This may be due to substances such as heam, nitrosamines, or glycosylated end products that may be damaging the beta cells.

— May Meleigy


  1. de Munter JS, Hu FB, Spiegelman D, Franz M, van Dam RM. Whole grain, bran, and germ intake and risk of type 2 diabetes: a prospective cohort study and systematic review.  PLOS Med. 2007;4:e261.
  2. Schulze MB, Liu S, Rimm EB, Manson JE, Willett WC, Hu FB. Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women. Am J Clin Nutr. 2004;80:348-56.
  3. Krishnan S, Rosenberg L, Singer M, et al. Glycemic index, glycemic load, and cereal fiber intake and risk of type 2 diabetes in US black women.  Intern Med. 2007;167:2304-9.
  4. Halton, TL., et al., Low-carbohydrate-diet score and risk of type 2 diabetes in women. Am J Clin Nutr, 2008. 87(2): p. 339-46.
  5. Hu EA,Pan A,Malik VSun Q. White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review. BMJ 2012;344:e1454
  6. Riserus U., Willett WC., and Hu FB., Dietary fats and prevention of type 2 diabetes. Prog Lipid Res, 2009. 48(1): p. 44-51.
  7. Malik VS, Popkin BM, Bray GA, Despres JP, Willett WC, Hu FB. Sugar-sweetened beverages and risk of metabolic syndrome and type 2 diabetes: a meta-analysis.  Diabetes Care. 2010;33:2477-
  8. Vartanian LR, Schwartz MB, Brownell KD. Effects of soft drink consumption on nutrition and health: a systematic review and meta-analysis. Am J Public Health. 2007;97:667-75.
  9. An P, Sun Q, Adam MB, Matthias BS, JoAnn EM, Walter Willet WC, and Hu FB. Red Meat Consumption and Risk of Type 2 Diabetes: 3 Cohorts of U.S. Adults and an Updated Meta-Analysis.  American Journal of Clinical Nutrition, online August 10, 2011.