Aging is associated with increased HbA 1c levels, independently of glucose levels and insulin resistance, and also with decreased HbA 1c diagnostic specificity

Measures of HbA 1c are used for screening and management, but HbA 1c levels rise with increasing age. Higher HbA 1c levels with increasing age cannot be attributed to unrecognized diabetes or prediabetes, postprandial hyperglycaemia or insulin resistance. Differences in HbA 1c levels with age are substantial: levels are 3.82 mmol/mol (0.35%) greater for an 80‐year‐old than for a 30‐year‐old individual, with the same glucose levels. The specificity of HbA 1c ‐based criteria for prediabetes decreases with increasing age. Screening with HbA 1c will tend to overdiagnose diabetes and prediabetes in older patients. Guiding management based only on HbA 1c levels might increase hypoglycaemia in older patients. Practitioners should monitor glucose as well as HbA 1c levels.