title: Low HbA1c and Increased Mortality Risk-is Frailty a Confounding Factor?
abstract: Diabetes mellitus is increasingly becoming an older person disease due to the increased survival and aging of the population. Previous studies which showed benefits of tight glycemic control and a linear relationship between HbA1c and mortality have largely included younger patients newly diagnosed with diabetes and with less comorbidities. Recent studies, which included older population with diabetes, have shown a U-shaped relationship of increased mortality associated with low HbA1c. The mechanism of such relationship is unclear. There was no direct causal link between low HbA1c and mortality. It appears that malnutrition, inflammation and functional decline are characteristics shared by the populations that showed increased mortality and low HbA1c. In these studies functional status, disability or frailty was not routinely measured. Therefore, although adjustment for comorbidities was made there may be a residual confounding by unmeasured factors such as frailty. Thus, frailty or decline in functional reserve may be the main confounding factor explaining the relationship between increased mortality risk and low HbA1c.
authors.affiliation: Consultant Physician and Honorary Senior Clinical Lecturer, Department of Elderly Medicine, Rotherham General Hospital, Rotherham, S60 2UD, UK.
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Abdelhafiz
authors.affiliation: Dean and Professor of Medicine, Institute of Diabetes for Older People (IDOP), Bedfordshire &, Hertfordshire Postgraduate Medical School, University of Luton, Puteridge Bury Campus, Bedfordshire, LU2 8LE, UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Sinclair
keywords: Diabetes; Frailty; Low HbA1c; Mortality