Glycated haemoglobin cutoff for diabetes diagnosis increases with age: Study
Glycated haemoglobin cutoff for diabetes diagnosis increases as the age advances, finds a new study.
Glycated haemoglobin (HbA1c ) increases with age in people without diabetes, finds a new study. Therefore disregarding age-related Glycated haemoglobin (HbA1c) increase may lead to diabetes mellitus (DM) misdiagnosis and overtreatment. The study has appeared in BMC Endocrine Disorders.
An HbA1c of 6.5% is recommended as the cut point for diagnosing diabetes. A value of less than 6.5% does not exclude diabetes diagnosed using glucose tests.HbA1c reflects average plasma glucose over the previous eight to 12 weeks. It can be performed at any time of the day and as compared to blood sugar measurement where special preparation such as fasting is required. These properties have made it the preferred test for assessing glycaemic control in people with diabetes.
Measurement of glycated haemoglobin A1c (HbA1c) plays a central role in monitoring the quality of antidiabetic therapy and in the diagnosis of diabetes. In daily practice, the advantages of HbA1c include less day to day variability during acute illness and greater convenience as fasting is not required compared to fasting blood sugar, postprandial blood sugar measurements and oral glucose tolerance tests.
The researchers enrolled Individuals without diabetes from 2 population-based cohorts. In total 4263 subjects from the Study of Health in Pomerania (SHIP-0); and 4402 from the independent study SHIP-Trend were studied.
- Cohorts examined and compared for age-specific HbA1c changes.
- Healthy subpopulations of SHIP-0 and SHIP-Trend were combined to derive HbA1c reference intervals by age group.
- Funding: Federal Ministry of Education and Research, Ministry of Cultural Affairs, Social Ministry of the Federal State of Mecklenburg-West Pomerania.
The researchers found that the reference intervals were derived from a healthy subpopulation with the upper reference limit (URL) for HbA1c of 42.1 mmol/Mol (6.0%) for individuals aged 20–39 years increasing to 43.2 mmol/Mol (6.1%) for individuals aged 40–59 years. For people aged ≥60 years the URL was 47.5 mmol/Mol (6.5%). In both study populations, an increase in HbA1c with age was observed. ANOVA revealed up to 8.5 mmol/Mol (0.77%) or 7.3 mmol/Mol (0.68%) higher estimated mean levels of HbA1c in the oldest compared to the youngest age group in SHIP-0 or SHIP-trend, respectively. Linear regression analyses confirmed the positive associations of HbA1c with age which was independent of BMI
1. Up to 0.78% or 0.67% higher estimated mean HbA1c levels for ages ≥60 years compared with 20-39 years in SHIP-0 or SHIP-Trend, respectively:
In Women ≥60 years:
- SHIP-0: 5.83% (95% CI, 5.77%-5.89%); and
- SHIP-Trend: 5.62% (5.57%-5.68%).
In Women 20-39 years:
- SHIP-0: 5.05% (4.99%-5.12%); and
- SHIP-Trend: 4.95% (4.89%-5.01%).
2. HbA1c upper reference limit was:
- 6.0% (42.1 mmol/mol) for individuals aged 20-39 years;
- 6.1% (43.2 mmol/mol) for ages 40-59 years; and
- 6.5% (47.5 mmol/mol) for ≥60 years.
The researchers concluded that the present study confirmed the previously observed increase of Glycated haemoglobin, HbA1c with increasing age in non-diabetic individuals. As a consequence, age-dependent reference values for HbA1c were derived from two large and well-defined reference populations. Implementation of them into daily practice may improve patient care and diagnosis of diabetes and reduce the risk of misdiagnosis and subsequent overtreatment of diabetes in elderly patients.
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