Increased HbA1c Identifies Rapid Kidney Function Deterioration in Diabetics

While poor glycemic control defined by higher HbA1c levels is associated with worse renal outcomes, the presence of diabetes independent of glycemic status is also associated with high risk of relatively rapid deterioration in renal function. Therefore, all patients with diabetes, regardless of their glycemic control, are a logical target for structured preventive interventions.

A team of scientists from the University of Melbourne (Melbourne, Australia) conducted a prospective observational cohort study with 4,126 adults aged at least 54 years who made two or more visits to Austin Hospital (Heidelberg, Australia) from 2013 to 2016 (median age, approximately 77 years; 41% women). Participants had estimated glomerular filtration rates of more than 30 mL/min/1.73 m² and “no prior history of renal replacement therapy” before study onset. The team analyzed data on HbA1c and eGFR from 465 days of median follow-up time.

Diabetes was diagnosed in 26% of the population and the scientists noted that stage 4 chronic kidney disease developed in 19% of those with diabetes and 13% of those without diabetes. Among adults with multiple hospital admissions, those with type 2 diabetes were more likely to have worsening renal function compared with those without diabetes.

An eGFR decrease of more than 50% was more likely to occur for participants with diabetes versus without diabetes. The team also noted a higher predicted adjusted probability for those with diabetes and an eGFR of at least 45 mL/min/1.73 m² before study onset. A “rapid decline in renal function,” which was characterized by an annual decrease in eGFR of more than 5 mL/min/1.73 m², was more likely to occur for participants with versus without diabetes particularly between the first and second year of follow-up.

Ending the study at an eGFR of 30 mL/min/1.73 m² was more likely for participants with diabetes compared with those without diabetes. The scientists noted that HbA1c at study onset did not affect the likelihood of ending at an eGFR of 30 mL/min/1.73 m², but that it became 7% more likely that a 50% eGFR decrease would occur and 11% more likely that a “rapid decline” would occur with each HbA1c increase of 1% at baseline.

Niloufar Torkamani, MD, PhD, FRACP, an endocrinology/general medicine physician and lead author of the study, said, “We found that the presence of diabetes and higher HbA1c levels were strongly and independently associated with adverse renal outcomes at follow-up. Such patients are at high risk of relatively rapid deterioration in renal function and are a logical target for structured preventive interventions.” The study was published on October 22, 2019 in the Journal of Diabetes and its Complications.

Related Links:
University of Melbourne
Austin Hospital