Glycated haemoglobin variability and risk of renal function decline in type 2 diabetes mellitus: An updated systematic review and meta‐analysis

Abstract Objective To assess the association between glycated haemoglobin (HbA1c) variability and risk of renal function decline in type 2 diabetes mellitus (T2DM). Research Design and Methods A comprehensive search was carried out in PubMed, Embase, Web of Science and the Cochrane Library (until 12 March 2024). The Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) statement guidelines were followed for this meta‐analysis. HbA1c variability was presented as indices of the standard deviation (SD), coefficient of variation (CV), HbA1c variability score (HVS) and haemoglobin glycation index (HGI). This meta‐analysis was performed using random‐effect models. Results Eighteen studies met the objectives of this meta‐analysis. The analyses showed positive associations between HbA1c variability and kidney function decline, with hazard ratio (HR) 1.26 (95% confidence interval [CI] 1.15–1.38) for high versus low SD groups, HR 1.47 (95% CI 1.30–1.65) for CV groups, HR 1.32 (95% CI 1.10–1.57) for HVS groups and HR 1.53 (95% CI 1.05–2.23) for HGI groups. In addition, each 1% increase in SD and CV was linked to kidney function decline, with HR 1.26 (95% CI 1.17–1.35), and 1.13 (95% CI 1.03–1.23), respectively. Also, each 1‐SD increase in SD of HbA1c was associated with deterioration in renal function, with HR 1.17 (95% CI 1.07–1.29). Conclusions The four HbA1c variability indicators were all positively associated with renal function decline progression; therefore, HbA1c variability might play an important and promising role in guiding glycaemic control targets and predicting kidney function decline progression in T2DM.