Macrovascular complications related to A1c in longstanding Type 1 diabetes

By Lisa Foster-McNulty, MSN, RN, CDE

Macrovascular but not microvascular complications seem related to A1c in longstanding Type 1 diabetes

According to research published in the September, 2016 issue of Diabetic Medicine, A1c levels are a predictor of macrovascular disease, independent of diabetes duration.  Wait a minute–didn’t we think that A1c doesn’t predict cardiovascular complications? 

Macrovascular disease refers to “the heart part” of complications, such as stroke and heart attack.  Microvascular complications are kidney, eye, and nerve damage.   Researchers set out to describe factors that are associated with the prevalence and absence of both types of complications in people with longstanding Type 1 diabetes.  They wanted to study the risk factors that are linked to the incidence of these complications. 

Study participants were people with Type 1 who were entered into the Swedish National Diabetes Register between 2002 and 2004.  This amounted to 18,450 people.  Researchers compared risk factor distribution in people with and without complications in people who had a diabetes duration of at least 50 years.  Then they studied the incidence of complications during a follow up period of 10 years in all the people who did not have complications at baseline.

Of the 1023 people with a diabetes duration of at least 50 years, 453 (44%) had macrovascular disease, 534 (52%) had microvascular disease, and 319 (31%) didn’t have any diabetes complications.  Gender, age, A1c, Body Mass Index (BMI), LDL cholesterol, HDL cholesterol, triglycerides, systolic blood pressure, protein in the urine, use of blood pressure medication, use of medication to control cholesterol levels, and income were all factors that differed significantly between people with and without macrovascular disease.  Except for gender and HDL cholesterol, the same factors differed significantly between people with and without microvascular disease.  In the follow up period, macrovascular disease was diagnosed in 6.1% of the study cohort, while 19.6% were diagnosed with microvascular disease.  The researchers found that the incidence of macrovascular disease was significantly associated with A1c levels.

The researchers determined that people who have lived with diabetes for at least 50 years without developing complications are significantly younger, have significantly lower A1c, BMI, and triglyceride levels than their counterparts who have diabetic complications.  A1c predicted macrovascular disease independent of the duration of diabetes duration.  No matter how you slice it, it makes sense to manage diabetes as well as you can to have the best control you can achieve.