Tight blood sugar control in type 2 diabetes linked to fewer heart attacks and strokes

Urmila Parlikar
Urmila Parlikar, Senior Content Editor, Harvard Health Publications

Diabetes damages every part of the body, from the brain to the feet. High blood sugar, the hallmark of diabetes, wreaks havoc on blood vessels. It makes sense that keeping blood sugar under control should prevent diabetes-related damage — but how low to push blood sugar is an open question.

A study published in today’s issue of The New England Journal of Medicine (NEJM) provides reassuring evidence that so-called tight blood sugar control is good for the heart and circulatory system.

“Tight blood sugar control represents a new age of diabetes care,” says Dr. David Nathan, professor of medicine at Harvard Medical School and director of both the General Clinical Research Center and the Diabetes Center at Massachusetts General Hospital.

The hazards of high blood sugar

Type 2 diabetes is marked by high levels of blood sugar. Over time, high blood sugar damages small blood vessels throughout the body. This is called microvascular disease. The damage can lead to kidney failure, nerve pain, amputation, and blindness.

But the leading cause of complications and death in people with diabetes is cardiovascular disease, which involves the body’s larger blood vessels. (This is also called macrovascular disease.) About two-thirds of people with diabetes die from heart disease, stroke, or other cardiovascular problems.

A good measure of blood sugar is the hemoglobin A1c (HbA1c) test. It reveals a person’s average blood sugar level over the previous three months. People without diabetes have an HbA1c level under 5.7%; an HbA1c level of 6.5% or greater usually indicates diabetes.

For some people with type 2 diabetes, a healthy diet and regular exercise can keep blood sugar in check, but many need medication as well. People with diabetes are usually urged to aim for tight blood sugar control, which translates into an HbA1c level below 7%.

Research has shown that tight blood sugar control can reduce the risk of microvascular complications. But the effect of tight blood sugar control on cardiovascular disease has been murkier. The new NEJM report suggests that tight blood sugar control also has cardiovascular benefits.

The benefits of tight control

The report is a 10-year follow-up of the Veterans Affairs Diabetes Trial. This trial enrolled 1,791 military veterans with type 2 diabetes who were an average of 60 years old. These veterans were randomly assigned to either “intensive” therapy intended to bring blood sugar down to a lower HbA1c target, or “standard” therapy with a higher HbA1c target. In each group, the target blood sugar level was achieved with a combination of oral diabetes medications and insulin injections, if needed.

During the five-and-a-half-year trial, the intensive-therapy group had an average HbA1c level near 6.9%. The standard-therapy group had an average HbA1c level near 8.4%.

More than 1,600 of the trial participants were followed for another five years. During this time, researchers compared how many participants had a cardiovascular event, such as heart attack or stroke, between the intensive therapy and standard therapy groups.

The results were heartening, both for doctors who have championed tight blood sugar control and for people with diabetes who have worked hard to achieve it. Heart attack and stroke risk in the tight control group was 17% lower than among those whose blood sugar levels floated a bit higher. That translates into nearly 9 fewer heart attacks and strokes per 1,000 people.

Metabolic memory

The study had another positive finding. It reinforced what Dr. Nathan calls “metabolic memory.” As he explains, “an early period of intervention seems to have durable effects over time.”

The active part of the VA trial lasted for about five-and-a-half years. After that, the veterans’ medical care was no longer supervised by the research study team. Within three years, the average HbA1c level in the intensive-therapy group had crept upward, reducing the difference in levels between the intensive and standard groups from 1.5% to somewhere between 0.2% and 0.3%. And yet, the intensive therapy group continued to reap cardiovascular benefits years later.

The effects of intensive treatment don’t last forever, cautions Dr. Nathan. At some point, he says, “metabolic memory becomes metabolic amnesia.” But the longer you keep blood sugar under tight control, the longer the benefits are likely to last.

Balancing act

Although tight blood sugar control can help prevent diabetes-related damage, it has some drawbacks. People aiming for tight control can experience bouts of low blood sugar (hypoglycemia), which can be very dangerous. Tight control can also be difficult to achieve, sometimes requiring multiple medications that may have harmful side effects of their own.

Earlier research had suggested that people with long-standing diabetes and established heart disease may not benefit from tight blood sugar control as much as those with newly diagnosed diabetes. But the new NEJM report shows that it’s never too late to control blood sugar. The veterans enrolled in this trial had had poorly controlled diabetes for several years before the study began. And 40% had cardiovascular disease when they enrolled in the trial. So not only did intensive treatment reduce cardiovascular disease risk, it did so in older people with long-standing diabetes, many of whom already had heart trouble.

Good blood sugar control is important for everyone with diabetes. Current guidelines from the American Diabetes Association recommend aiming for an HbA1c level of less than 7%. But the guidelines also recognize there’s no one-size-fits-all rule. If you have diabetes, ask your doctor if tight blood sugar control is right for you.

Related Information: Healthy Eating for Type 2 Diabetes

Comments:

  1. Chusnul

    This nice article, because I know abaout Tight Blood Sugar

  2. Dr. Sunny Sharma

    Very informative article, It shows a lot of facts and admiring content.

  3. Prashant Pandey

    Thanks for sharing information it will help lots of people to get aware.

  4. Sara

    I was diagnosed with type 2 Diabetes and put on Metformin on June 26th, 2014. I started the ADA diet and followed it 100% for a few weeks and could not get my blood sugar to go below 140. Finally i began to panic and called my doctor, he told me to get used to it. He said I would be on metformin my whole life and eventually insulin. At that point i knew something wasn’t right and began to do a lot of research. On April 13th I found this book on wje592.com/i-am-finally-free-of-diabetes/. I read the book from end to end that night because everything the writer was saying made absolute sense. I started the diet that day and the next morning my blood sugar was down to 100, the next day was in the 90’s and now i have a fasting blood sugar between Mid 70’s and the 80’s. My doctor took me off the metformin after just one week of being on this lifestyle change. I have lost over 30 pounds in a month. I now work out twice a day and still have tons of energy. I have lost 6+ inches around my waist and I am off my high blood pressure medication too. I have about 20 more pounds to go till my body finds its ideal weight. The great news is, this is a lifestyle I can live with, it makes sense and it works. God Bless the writer. I wish the ADA would stop enabling consumers and tell them the truth. You can get off the drugs, you can help yourself, but you have to have a correct lifestyle and diet. No more processed foods.

  5. Mary Patterson

    Tight blood sugar is benefit for a lot of diseases. I was diagnosed with type 2 Diabetes and put on Metformin on June 26th, 2014. I started the ADA diet and followed it 100% for a few weeks and could not get my blood sugar to go below 140. Finally i began to panic and called my doctor, he told me to get used to it. He said I would be on metformin my whole life and eventually insulin. At that point i knew something wasn’t right and began to do a lot of research. I read the book from end to end that night because everything the writer was saying made absolute sense. I started the diet that day and the next morning my blood sugar was down to 100, the next day was in the 90’s and now i have a fasting blood sugar between Mid 70’s and the 80’s. My doctor took me off the metformin after just one week of being on this lifestyle change. I have lost over 30 pounds in a month. I now work out twice a day and still have tons of energy. I have lost 6+ inches around my waist and I am off my high blood pressure medication too. I have about 20 more pounds to go till my body finds its ideal weight. The great news is, this is a lifestyle I can live with, it makes sense and it works. God Bless the writer. I wish the ADA would stop enabling consumers and tell them the truth. You can get off the drugs, you can help yourself, but you have to have a correct lifestyle and diet. No more processed foods.

  6. Anthony cusano

    So, intensive therapy reduces the number of cardiovascular events, but causes deaths from both CV disease and all causes by some other problems. The conclusion is that reducing blood sugar is a good thing, but using poisons (all medications technically poison bodily processes) is the wrong way to do it. We physicians need to end our love affair with poisons, and enable our patients to reduce CV risk factors the natural way, i.e. by diet and exercise. Just because we suck at doing that doesn’t mean we are right to use sorcery. All the poisons do in this case is reshuffle the deck so patients just die from different problems at the same rate, while big pharma and healthcare financing companies reap profits selling drugs or spending fewer premium dollars on patient care, respectively.

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