Pulses and Diabetes

Diane H. Morris, PhD, RD, Mainstream Nutrition, Toronto ON, and Kelley Fitzpatrick, MSc, NutriTech Consulting, Winnipeg MB, for Pulse Canada, and Nancy Longnecker, PhD, CLIMA, The University of Western Australia

Pulses, which include beans, peas, chickpeas and lentils, are high-fibre, low-fat foods with a low glycemic index (GI) that may help people control their blood glucose levels. 1 Maintaining a near-normal blood glucose level is the first goal of diet therapy in treating diabetes.2

The Key Issue in Diabetes Is Managing Blood Glucose

One of the characteristics of diabetes mellitus is a high blood glucose level (hyperglycemia). People with diabetes experience disturbances in blood glucose that can result from problems with insulin secretion by the pancreas and/or problems with the actions of insulin in muscle and other tissues. Chronic hyperglycemia is a serious health matter because it damages various organs, particularly the eyes, kidneys, nerves, heart and blood vessels. Type 2 diabetes - formerly called non-insulin-dependent diabetes or adult-onset diabetes - is the most common form, affecting about 90% of individuals with diabetes. The risk of developing Type 2 diabetes increases with age, obesity and a sedentary lifestyle.3

Pulses in Diabetes Diet Management - The Evidence

A diet that produces hyperglycemia and a greater demand for insulin increases the risk of Type 2 diabetes. Individuals with or at risk of Type 2 diabetes are advised to eat a diet in which about 50-60% of energy is supplied by carbohydrates obtained mainly from whole grains, fruit, vegetables and low-fat milk.2,4 Pulses make an important contribution to healthy eating because their effect on blood glucose is less than that of most other carbohydrate-containing foods.

In one study, nine adults with Type 2 diabetes ate dried peas as part of a mixed meal and then later ate a mixed meal made with potatoes. Their blood glucose and insulin levels were lower after eating the mixed meal made with dried peas than after eating the mixed meal made with potatoes.5 A different study looking at healthy people found that those eating a chickpea-based meal had lower blood glucose and insulin levels than those eating wheat-based meals (either a whole grain plus wheat bran or white bread).6 These findings and others show that pulses can be useful for diabetics because they cause less of a rise in blood glucose than potatoes or wheat-based foods.

Pulses Have a Low Glycemic Index

Twenty years ago, when the concept of the glycemic index was first being developed, researchers were surprised to discover that baked potatoes had a higher GI value and, therefore, a greater effect on blood glucose than ice cream! Today, the GI values for hundreds of foods are known.1,7 For instance, baked and instant potatoes, corn flakes, French fries and plain bagels have a high GI of 70 or more, meaning they raise blood glucose more than other foods. Pulses like lentils, kidney beans, split peas and chickpeas have a low GI of 55 or less, indicating that their effect on blood glucose is less than that of many other carbohydrate-containing foods.8 The lower the food's glycemic index, the better the blood glucose control.

The Glycemic Index of Some Common Foods

High GI Foods Low GI Foods
Food Glycemic Index* Food Glycemic Index*
White rice, boiled 45 - 104 Baked beans 40 - 56
Boiled potato 54 - 101 Lentils (boiled) 18 - 52
Corn flakesTM 72 - 92 Apple (raw) 28 - 44
White bread 67 - 87 Chickpeas (dried, boiled) 36
Jelly beans 76 - 80 Yoghurt 14 - 36
Porridge (from whole rolled oats) 42 - 75 Hommos 6

* Values from www.glycemicindex.com 1

The glycemic index is a method of ranking carbohydrate foods by their ability to raise blood glucose following a meal. To determine a food's GI, a standard amount of the test food is eaten, and then the rise in blood glucose is compared with that of an equivalent amount of a standard or reference food (white bread or pure glucose). The reference food is given a GI value of 100. The GI values differ according to which food was used as the reference food. For example, when glucose was the reference food in a Canadian study, sweet corn had a GI of 59; when white bread was the reference food, it had a GI of 84. Glucose was the reference food for the items listed in the table above.

Pulses Help People Control Blood Glucose

Pulses have a low glycemic index, making them excellent sources of carbohydrate in the diet of those affected by diabetes.1,7,9 Including pulses in the diet helps control blood glucose and insulin levels. Pulses have other health effects, like reducing blood lipids. This may help prevent some serious complications of diabetes.10 Once referred to as "poor man's meat"10 because they are high in protein and inexpensive, pulses are valuable additions to a modern diet because of their good taste, convenience, ease of use and nutritional role in managing and preventing diabetes.11

References

  1. University of Sydney GI Website. www.glycemicindex.com
  2. Wolever T, Barbeau M-C, Charron S, et al. 1999. Guidelines for the nutritional management of diabetes mellitus in the new millennium: A position statement by the Canadian Diabetes Association. Can. J. Diab. Care 23: 56-69. Available online: www.diabetes.ca/Files/nutritional_guide_eng.pdf
  3. Expert Committee. 2003. Report of the Expert Committee on the diagnosis and classification of diabetes mellitus. Diabetes Care 26 (suppl 1): S5-S20.
  4. American Diabetes Association. 2003. Evidence-based nutrition principles and recommendations for the treatment and prevention of diabetes and related complications. Diabetes Care 26 (suppl 1): S51-S61.
  5. Schäfer G, Schenk U, Ritzel U, et al. 2003. Comparison of the effects of dried peas with those of potatoes in mixed meals on postprandial glucose and insulin concentrations in patients with type 2 diabetes. Am. J. Clin. Nutr. 78:99-103.
  6. Nestel, P, Cehun, M and Chronopoulos, A. 2004. Long-term consumption and single meal effects of chickpeas on plasma glucose, insulin and triacylglycerol. Am. J. Clin Nutr. In press.
  7. Foster-Powell K, Holt SHA and Brand-Miller JC. 2002. International table of glycemic index and glycemic load values: 2002. Am. J. Clin. Nutr. 76: 5-56.
  8. Canadian Diabetes Association. 2002. Glycemic Index - The Index in Depth. www.diabetes.ca/Section_About/glycemic.asp
  9. Go Grains - Grains Nutrition Glycaemic Index. www.gograins.grdc.com.au/grainsnutrition/ie/15frame.html
  10. Rizkalla SW, Bellisle F, Slama G. 2002. Health benefits of low glycaemic index foods, such as pulses, in diabetic patients and healthy individuals. Br. J. Nutr. 88 (suppl 3): S255-S262.
  11. Leterme P. 2002. Recommendations by health organizations for pulse consumption. Br. J. Nutr. 88 (suppl 3): S239-S242.