HbA1c detects diabetes, adverse lipids otherwise missed by FPG
MedWire News: Introducing glycated hemoglobin (HbA1c) into diabetes diagnostic criteria allows detection of previously undiagnosed cases of diabetes among Japanese individuals, report researchers.
In addition, those diagnosed by HbA1c are characterized by unfavorable lipid profiles reflecting an atherosclerotic trait that is not determined by fasting plasma glucose (FPG), write the researchers in the journal Diabetes Research and Clinical Practice.
"HbA1c reflects chronic hyperglycemia, including postprandial glucose spikes, rather than acute dysglycemia, which is assessed by FPG," explains the team. "Therefore, individuals classified as having diabetes by HbA1c might have different demographic and cardiovascular profiles than those with diabetes according to FPG criterion."
Led by Hirohito Sone (University of Tsukuba, Ibaraki, Japan), the researchers performed a cross-sectional study of 26,884 individuals, aged 18-91 years, who had undergone a routine medical checkup at Toranomon Hospital, Tokyo.
The participants were divided into four groups according to the presence or absence of FPG of 7.0 mmol/L or more and HbA1c of 6.5% or more, in line with American Diabetes Association (ADA) criteria.
Prevalence of undiagnosed diabetes in the overall cohort was 3.6%.
However, 0.9% of the new cases were identified only by the HbA1c and not the FPG criterion.
Among people with diabetes, only 47.5% fulfilled both the HbA1c and FPG criteria. In individuals where diabetes was detected by HbA1c or FPG alone, there was no significant difference in the number of cases missed by each technique.
The authors note that unfavorable lipid profiles were more frequent when the HbA1c criterion was used than when only the FPG criterion was used.
Of the individuals with diabetes diagnosed by HbA1c alone, only 24.0% had HDL cholesterol of 1.55 mmol/L or more and only 10.2% had LDL cholesterol of less than 2.59 mmol/L, which is the therapeutic goal recommended by the ADA.
Furthermore, 21.7% had LDL cholesterol levels of 4.14 mmol/L or more.
"Our study results suggested that introducing the HbA1c criterion into the diagnostic criterion could capture atherosclerotic lipid abnormalities that were not assessed by FPG values alone," write Sone et al.
However, they say they cannot suggest a reasonable cutoff value for the HbA1c criterion to diagnose diabetes from this cross-sectional study.
"Further research is needed, including data on the oral glucose tolerance test, or a prospective investigation that includes the assessment of vascular complications," they conclude.
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By Sally Robertson