Richard K. Bernstein, MD, FACE, FACN, FACCWS
RECENT DEVELOPMENTS REGARDING RISK FACTORS FOR HEART DISEASE
FACTORS FOR HEART DISEASE
Diabetics die from heart failure at a rate far exceeding that of people with normal glucose tolerance. Heart failure involves a weakening of the cardiac muscle so that it cannot pump enough blood. Most long term, poorly controlled diabetics have a condition called cardiomyopathy. In diabetic cardiomyopathy, the muscle tissue of the heart is slowly replaced by scar tissue over a period of years. This weakens the muscle so that it eventually “fails.” There is no evidence linking cardiomyopathy with dietary fat intake or serum lipids.
A fifteen-year study of 7,038 French policemen in Paris reported that “the earliest marker of a higher risk of coronary heart disease mortality is an elevation of serum insulin level.” A study of middle aged nondiabetic women at the University of Pittsburgh showed an increasing risk of heart disease as serum insulin levels increased. Other studies in nondiabetics have shown strong correlations between elevated serum insulin levels and other predictors of cardiac risk such as hypertension, elevated triglyceride, and low HDL. The importance of elevated serum insulin levels (hyperinsulinemia) as a cause of heart disease and hypertension has taken on such importance that a special symposium on this subject was held at the end of the 1990 annual meeting of the ADA. A report in a subsequent issue of the journal Diabetes Care quite appropriately points out that “there are few available methods of treating diabetes that do not result in systemic hyperinsulinemia [unless the patient is following a low-carbohydrate diet].” Furthermore, research published in the journal Diabetes in 1990 demonstrated that elevated serum insulin levels cause excessive leakage of protein from small blood vessels. This is a common factor in the etiology of blindness (via macular edema) and kidney disease in diabetics.
Although the AHA and the ADA have been recommending lowfat, high-carbohydrate diets for diabetics for many decades, no one had compared the effects on the same patients of low- versus high carbohydrate diets until the late 1980s. Independent studies performed in Texas and California demonstrated lower levels of blood sugar and improved blood lipids when patients were put on lower-carbohydrate, high-fat diets. It was also shown that, on average, for every 1 percent increase in HgbA1C (the test for average blood sugar over the prior four months), total serum cholesterol rose 2.2 percent and triglycerides increased 8 percent. A long-term study of 7,321 “nondiabetics” in 2006 showed that for every 1 percent increase in HgbA1C above 4.5 percent, the incidence of coronary artery disease increased 2.5-fold. The same study also showed that for every 1 percent increase in HgbA1C above 4.9 percent, mortality increased by 28 percent.
The National Health Examination Follow-Up Survey, which followed 4,710 people, reported in 1990 that “in the instance of total blood cholesterol, we found no evidence in any age-sex group of a risk associated with elevated values.” That’s right: they found no risk associated directly with elevated total cholesterol. On the same page, this study lists diabetes as by far the single most important risk factor affecting mortality. In males aged 55–64, for example, diabetes was associated with 60 percent greater mortality than smoking and double the mortality associated with high blood pressure.
The evidence is now simply overwhelming that elevated blood sugar is the major cause of the high serum lipid levels among diabetics and, more significantly, the major factor in the high rates of various heart and vascular diseases associated with diabetes. Many diabetics were put on low-fat diets for so many years, and yet these problems didn’t stop. It is only logical to look to elevated blood sugar and hyperinsulinemia for the causes of what kills and disables so many of us.
My personal experience with diabetic patients is very simple. When we reduce dietary carbohydrate, blood sugars improve dramatically. After several months of improved blood sugars, we repeat our studies of lipid profiles and thrombotic risk factors. In the great majority of cases, I see normalization or improvement of abnormalities.* This parallels what happened to me more than thirty-five years ago, when I abandoned the high-carbohydrate, low-fat diet that I had been following since 1946.
Sometimes, months to years after a patient has experienced normal or near-normal blood sugars and improvements in the cardiac risk profile, we will see deterioration in the results of such tests as those for LDL, HDL, homocysteine, and fibrinogen. All too often, the patient or his physician will blame our diet. Inevitably, however, we find upon further testing that his thyroid activity has declined. Hypothyroidism is an autoimmune disorder, like type 1 diabetes, and is frequently inherited by diabetics and their close relatives. It can appear years before or after the development of diabetes and is not caused by high blood sugars. In fact, hypothyroidism can cause a greater likelihood of abnormalities of the cardiac risk profile than can blood sugar elevation. The treatment of a low thyroid condition is oral replacement of the deficient hormone(s)—usually one pill daily. The best screening test is free T3, tested by tracer dialysis. If this is low, then a full thyroid risk profile should be performed. Correction of the thyroid deficiency inevitably corrects the abnormalities of cardiac risk factors that it caused.
* If your physician finds all of this hard to believe, he or she might benefit from reading the seventy articles and abstracts on this subject contained in the Proceedings of the Fifteenth International Diabetes Foundation Satellite Symposium on “Diabetes and Macrovascular Complications,”Diabetes 45, Supplement
3, July 1996. Also worth reading is “Effects of Varying Carbohydrate Content of Diet in Patients with Non-Insulin Dependent Diabetes Mellitus,” by Garg et
al., Jnl Amer Med Assoc 1994; 271:1421–1428. Many studies comparing lowcarbohydrate and low-fat diets are presented each year at meetings of the Metabolism and Nutrition Society. The low-carbohydrate diets invariably have shown reduced cardiac risk.
We would like to thank the publisher Little Brown and Company and Dr. Richard K. Bernstein, for allowing us to provide excerpts from The Diabetes Diet.
Copyright © 2005 by Richard K. Bernstein, M.D. All rights reserved. No part of this book may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review.
This book is not intended as a substitute for professional medical care. The reader should regularly consult a physician for all health-related problems and routine care.
For more information on Dr. Bernstein’s and to purchase his books, CD’s or get access to his free monthly webinars, visit his website at DiabetesBook.com.