Insulin Resistance Facts

Two thirds of patients with diabetes mellitus (Type 2 DM), or adult onset diabetes, will die of cardiovascular disease. Much of the increased risk from cardiovascular disease in Type 2 DM results from insulin resistance. People who have insulin resistance, even though their blood sugar levels remain in the normal range, are still at much higher risk for cardiovascular disease. Insulin resistance syndrome is strongly related to body weight and occurs when there is a reduced ability of insulin to control blood sugar. People who are heavier must produce more insulin than people who are slender, on average, even in the fasting state, in order to maintain normal blood-sugar levels. However, insulin resistance can occur in normal weight individuals, particularly if they are unfit. Insulin resistance often leads to a host of risk factors for cardiovascular disease, including elevated triglycerides, decreased HDL or “good cholesterol,” hypertension and hyperinsulemia. Collectively, these are called insulin resistance syndrome (IRS) or simply syndrome X.1

What Diet Is Best For People With IR? Weight loss reduces insulin resistance. It also lowers triglycerides, raises HDL levels and also greatly decreases the risk of developing Type 2 DM. A diet lower in fat and higher in unrefined carbohydrates, such as vegetables, fruits, whole grains and beans, appears to aid weight loss compared to a high-fat diet or a diet that is high in sugar and refined carbohydrates, e.g. baked goods, cookies, candies, sweetened cereals, etc. Increased physical activity is a must for people trying to lose weight and keep it off. Exercise also decreases insulin resistance, but much of this effect wears off in a day so it is best to walk 2-3 miles each day. Saturated fatty acids and cholesterol, found mainly in whole fat dairy products and meats, should be greatly reduced in all people at high risk for coronary artery disease. This obviously includes people with insulin resistance and/or Type 2 DM. Increasing dietary fiber has been shown to improve both blood lipids and blood sugar regulation even when it doesn’t result in weight loss.2 Legumes, whole grains, fruits and vegetables are all good sources of fiber. High-fat diets have been implicated in the development of insulin resistance and problems with blood sugar regulation since the 1930s.3, 4 A study of 1173 men and women found that insulin resistance increased over time in those who consumed more dietary fat (regardless of the type of fat), particularly in individuals at increased risk of developing Type-2 DM because of obesity.5 In studies where subjects ate as much as they wanted, a higher carbohydrate diet was superior to a diet higher in unsaturated fat in terms of reducing heart disease risk factors.6, 7 When subjects ate as much as they wanted of a high-fiber, high-carbohydrate diet they lost weight and significantly reduced several major risk factors for heart disease. 8 A high-fiber, high-carbohydrate diet, coupled with regular exercise, is the key to long-term weight control. In those with Type 2 DM who are slender, consuming more nuts, seeds, avocados and modest amounts of unsaturated oils is certainly preferable to eating more refined carbohydrates and may even be better than trying to stuff oneself with healthier high-carbohydrate foods. The Bottom Line Most people with IR and Type 2 DM are overweight. Losing weight and keeping it off is likely to be more successful on a low-fat, high-fiber diet coupled with regular exercise than simply trying to eat fewer calories from typical American fare. A diet with plenty of fruits, vegetables, whole grains and non-fat dairy products plus a little fish and limited salt lowers blood sugar, LDL and blood pressure levels in patients with or without Type 2 DM.By James J. Kenney, PhD, RD, FACN. Dr. Kenney is the Nutrition Research Specialist for the Pritikin Longevity Center in Santa Monica California. You can view many of his full text articles, and accompanying CPE courses on our website at www.foodandhealth.com - click on CPE Courses. We now offer easy online testing and you can read the articles for free. Dr. Kenney is currently working on a CPE course and presentation kit for diabetes and heart disease - it should be ready by August - we’ll keep you posted. References: 1. Reaven GM. Clinical Diabetes 1994; March/April:32-6 2. Chandalia M, Garg A, Lutjohann D, et al. N Engl J Med 2000;342:1392-8 3. Himsworth HP. Clin Sci 1935;2:67-94 4. Tremblay A. Int J Obes 1995;19 (suppl 1):S60-8 5. Mayer-Davis EJ, Monaco JH, Hoen HM, et al. Am J Clin Nutr 1997;65:79-87 6. Schaefer EJ, Lichtenstein AH, Lamon-Fava S, et al. JAMA 1995;274:1450-5 7. Lichtenstein AH, Ausman LM, Carrasco W, et al. Arterioscler Thromb 1994;14:1751-60 8. Beard C, Barnard JB, Robbins DC, et al. Arterioscler Thromb Vasc Biol 1996;16:201-7