Early and more intensive treatment for type 1 diabetes reduces the risk for long-term cardiovascular and kidney complications, according to a new study based on decades of data and published in the journal Diabetes Care.
Cardiovascular complications of diabetes — also sometimes known as macrovascular complications, since they refer to issues involving larger blood vessels — are one major category of problems that can occur from long-term exposure to elevated blood glucose levels. At the same time, diabetic kidney disease is a common example of microvascular complications, or issues involving small blood vessels. Damage to tiny blood vessels can also lead to diabetic retinopathy (eye disease). A third major category of diabetes complications, neuropathy (nerve damage), was not a main subject of the latest study.
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As noted in an article on the study at Endocrinology Advisor, researchers looked at data from two large long-term clinical trials. The first was the Diabetes Control and Complications Trial (DCCT), which lasted from 1983 to 1993, and the second was the Epidemiology of Diabetes Interventions and Complications (EDIC) trial, which started in 1994 and is ongoing. Overall, the researchers found a near-linear relationship between participants’ average A1C level (a measure of long-term blood glucose control) and their risk for both cardiovascular disease and reduced kidney function.
Early intensive control yields significant long-term benefits
Over a 20-year follow-up period, the cumulative risk for cardiovascular disease among participants who maintained an average A1C level of 9% was 15.3%. For participants who saw their A1C drop to 7% during the second half of the 20-year period, the cumulative risk for cardiovascular disease dropped to 12.4%. For participants who maintained an A1C level of 7% during the entire 20-year period, the risk for cardiovascular disease was only 7.7% — showing that early intensive blood glucose control is linked to a much larger benefit than achieving this level of control after 10 years. Even for participants who maintained an A1C level of 7% for the first 10 years then saw this level increase to 9% during the next 10 years, the cumulative risk for cardiovascular disease was only 9.0% — showing that earlier intensive control appears to be more beneficial than later intensive control, even if this level of control is not maintained beyond 10 years.
When it came to the risk for reduced kidney function — as measured by estimated glomerular filtration rate (eGFR) — there was a similar pattern. Participants who maintained an A1C level of 9% for 20 years had a cumulative risk for reduced kidney function of 18.1%. For those whose A1C level dropped to 7% for the second half of that period, the cumulative risk for reduced kidney function dropped to 14.5%. Those who maintained an A1C level of 7% for the entire period had only a 4.9% risk for reduced kidney function, while those who started out at that level of control but had an average A1C level of 9% for the second half of the study period had a 6.9% cumulative risk for reduced kidney function.
The researchers concluded that earlier interventions to achieve intensive blood glucose control may lead to large long-term benefits in people with type 1 diabetes. At the same time, there appear to be smaller benefits from intensive control at any point in time — so it’s never too late to take steps to reduce the risk for diabetes complications like cardiovascular disease and kidney disease.
Want to learn more about keeping your kidneys healthy with diabetes? Read “How to Keep Your Kidneys Healthy,” “Kidney Disease: Your Seven-Step Plan for Prevention” and “Ten Things to Know About Kidney Disease.”
Want to learn more about protecting your heart? Read “Be Heart Smart: Know Your Numbers,” “Does Diabetes Hurt Your Heart?” “Fight Off Heart Disease With These Five Heart-Healthy Foods” and “Lower Your Risk of Heart Disease.”