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HbA1c levels, CV events modestly related in type 2 diabetes
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A modest, but not statistically significant, relationship was found between HbA1c levels and cardiovascular events in people with type 2 diabetes, according to recent study findings published in Diabetes Care.
There was no difference in relationship among people with or without clinical manifestation of vascular disease, according to the researchers.
Jan Westerink, MD, PhD, of the University Medical Centre Utrecht in the Netherlands, and colleagues evaluated data from the Second Manifestations of Arterial Disease (SMART) study on 1,687 adults (mean age, 60.2 years) with type 2 diabetes, with and without vascular disease, to determine the relationship between glycemic control and new CV events and mortality. Follow-up was conducted for a median of 6.1 years.
Jan Westerink
During follow-up, 293 participants experienced a new CV event, and 189 died as a result of vascular disease; 340 participants died of all causes.
There was a nonsignificant relationship between CV events and higher levels of HbA1c in all participants (HR = 1.06; 95% CI, 0.97-1.17). Similarly, no relationship was found for participants with type 2 diabetes and vascular disease at baseline (HR = 1.03; 95% CI, 0.93-1.15). A strong relationship was found between HbA1c levels and CV events in participants without vascular disease (HR = 1.27; 95% CI, 1.06-1.51).
There was a 16% higher risk for all-cause mortality with each 1% increase in HbA1c in participants with diabetes and manifest vascular disease (HR = 1.16; 95% CI, 1.06-1.28); a similar relationship was found among those without vascular disease (HR = 1.13; 95% CI, 0.97-1.31).
“These cohort data do not necessarily preclude the possibility of clinical benefit of more stringent glycemic control on macro- and especially microvascular complications in these patients,” Westerink told Endocrine Today. “However, when the primary focus is a reduction of the risk for macrovascular disease in patients with type 2 diabetes (with vascular disease) by means of improving glycemic control, one should take into account the absence of the relation between glycemic control and clinical outcome in this study. Further research on the best approach for risk reduction in these very high risk patients is needed, including evidence to support clinicians in predicting which exact patient with type 2 diabetes would probably benefit most from improved glycemic control.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
Perspective
Back to TopPat Rafferty, PharmD, BCPS, CDE
Jan Westerink and colleagues at the University Medical Centre in the Netherlands prospectively followed 1,687 adult patients with type 2 diabetes enrolled in the Second Manifestations of Arterial Disease (SMART) study, a single-center cohort study, for a median of 6.1 years. HbA1c was measured at baseline, and patients filled out a questionnaire biannually related to vascular events including vascular death, stroke, myocardial infarction and the composite of these events. Sensitivity analyses used to determine the relation between HbA1c and cardiovascular events included smoking status, blood pressure, diabetes duration, cholesterol, and the use of anti-platelet therapies, glucose-lowering medications, blood pressure-lowering treatment and statins.
During follow-up, 293 patients had a new CV event; of these, 189 died of a vascular cause, while 340 patients died of all causes. Findings included a non-significant relationship between CV events and higher A1cs in all participants (HR = 1.06; 95% CI, 0.97 – 1.17). No relationship was found for participants with vascular disease at baseline (HR = 1.03; 95% CI, 0.93-1.15). A strong relationship was found between HbA1c levels and CV events in participants without vascular disease (HR = 1.27; 95% CI, 1.06-1.51). Patients with vascular disease had a 16% higher risk of all-cause mortality per 1% increase in HbA1c (HR 1.16;95% CI, 1.06 – 1.28) while a non-significant relation was found in patients without vascular disease (HR 1.13; 95% CI, 0.97 – 1.31).
The authors note that the results should be seen as hypothesis generation; weaknesses include the use of baseline HbA1c only and potentially insufficient power. The relationship between HbA1c and CV events has been well established by the Norfolk observational trial and UKPDS, albeit in a younger population than the SMART trial. The results of the SMART trial do not help answer the question of how critical glycemic control is in patients with and without vascular disease and established Type 2 diabetes.
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