CVD incidence high among people living with diabetes for 50+ years
medwireNews: People who live with type 1 diabetes for more than 50 years are at least four times more likely to have cardiovascular disease (CVD) than their diabetes-free peers, even when they have normal urinary albumin levels, study findings indicate.
Per-Henrik Groop (University of Helsinki, Finland) and colleagues say the data from the Finnish Diabetic Nephropathy Study (FinnDiane) “emphasize the need for lifelong meticulous glycemic control and suggest decreasing HbA1c [glycated hemoglobin] variability might be beneficial.”
The FinnDiane 50-year cohort included 729 individuals who had a median diabetes duration of 39.3 years at their baseline visit and 54.5 years at the end of follow-up. All were diagnosed with diabetes in 1967 or earlier.
The researchers report that these people had a 50-year cumulative CVD incidence of 38.7%, which was similar to the incidence of 39.7% they observed in a Finnish national comparison cohort of 1764 individuals diagnosed with type 1 diabetes between 1965 and 1967.
For the individual CVD components, the 50-year cumulative incidence of coronary artery disease (CAD), peripheral artery disease (PAD), and stroke in the FinnDiane 50-year cohort were 24.7%, 14.1%, and 12.6%, respectively. The corresponding rates at 60 years reached 48.6%, 29.7%, and 23.6%.
Groop and team also found that the incidence of CVD during the 16.6-year follow-up period was 7.4 times higher in the FinnDiane 50-year cohort than in 12,710 matched individuals without diabetes. The standardized incidence ratios (SIRs) for CAD, PAD, and stroke events were 7.2, 20.4, and 3.3, respectively.
And the investigators note that even among the 49.3% of the cohort who had normoalbuminuria (albumin excretion rate <20 µg/min or <30 mg/24 h), the CVD incidence was 4.9 times higher than that in the control group.
The strongest predictor of CVD was the presence of diabetic kidney disease, which was associated with a significant 1.81-fold increased risk.
In addition, each unit increase in triglyceride to high-density lipoprotein cholesterol ratio and mean HbA1c was associated with significant 1.36- and 1.26-fold increased risks for incident CVD, while per unit increases in HbA1c variability, age, and diabetes duration were each associated with significant 1.04-fold increased CVD risks.
Groop et al note that “an especially strong association was found between glycemic control and PAD, which is a relatively neglected complication of [type 1 diabetes].” In this case, a 1% increase in HbA1c was associated with a significant 1.50-fold increased risk for PAD.
The authors also point out in Diabetes Care that dyslipidemia was the only modifiable risk factor that was independently associated with all CVD events. They say that “this may suggest that lipid-lowering therapy should be much more aggressive in [type 1 diabetes] and that lower lipid targets as well as therapies focused on additional lipid subclasses are needed.”
In terms of mortality, individuals in the FinnDiane 50-year cohort were 3.2 times more likely to die during follow-up than expected, with CVD the most common cause of death.
The researchers comment that “[h]istorically, it was suggested that individuals surviving decades with [type 1 diabetes] might be protected from the adverse effects of hyperglycemia and may therefore be treated less intensively.”
They add: “Our results, however, suggest a strong association of HbA1c with incident CVD (especially PAD), even after very long diabetes duration, implying that glycemic control is crucial not only for the prevention or initiation but also for the perpetuation of the atherosclerotic process.”
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