Patients with type 2 diabetes at higher risk for AKI, even without pre-existing kidney disease

The authors of the retrospective study called for additional research on the pathogenesis of acute kidney injury (AKI) and the associated risk factors, such as medications, in diabetic patients.

Patients with type 2 diabetes are at higher risk for acute kidney injury (AKI) than those without it, and this risk extends to those without pre-existing chronic kidney disease (CKD), a study found.

Researchers used data from GoDARTS (Genetics of Diabetes Audit and Research in Tayside Study) in Scotland to perform a retrospective cohort study of patients with or without type 2 diabetes. The goal of the study was to determine rates of AKI and their relationship to CKD status, as well as whether the association between AKI and decline in glomerular filtration rate differs among those with diabetes and those without. The primary outcome, number of AKI episodes per person during follow-up, was used to calculate AKI episode rates per 1,000 patients per year and AKI rate ratios in patients with type 2 diabetes versus those without, depending on CKD status. The secondary outcome was decline in estimated glomerular filtration rate (eGFR) over time. Results of the study were published Sept. 18 by the Journal of the American Society of Nephrology.

The study cohort included 16,700 patients, 9,417 with type 2 diabetes and 7,283 without. A total of 47.2% of patients were women, and mean age at recruitment was 64.3 years. Overall, 2,504 patients with type 2 diabetes and 665 of those without had CKD at study recruitment (26.6% vs. 9.1%). Over a median of 8.2 years of follow-up, patients with diabetes were more likely than controls to develop AKI (48.6% vs. 17.2%, respectively) and to have pre-existing CKD or to develop CKD during follow-up (46.3% vs. 17.2%, respectively). In patients without CKD, the AKI rate was 121.5 per 1,000 person-years in those with diabetes and 24.6 per 1,000 person-years in those without. In patients with CKD, the AKI rate was 384.8 per 1,000 person-years in those with diabetes versus 180.0 per 1,000 person-years in those without diabetes after CKD diagnosis, and 109.3 per 1,000 person-years versus 47.4 per 1000 person-years, respectively, before CKD onset in those developing CKD after study recruitment. Slope of the eGFR decline before episodes of AKI was steeper in patients with diabetes than in controls, and after AKI episodes, the slope of decline in eGFR grew steeper in patients with diabetes but not in patients with diabetes and pre-existing CKD.

The authors noted that their study could have been affected by selection bias and that some cases of AKI may have been misclassified. They concluded that their study helps to quantify AKI risk in patients with diabetes as well as the condition's relationship to CKD. “The risk of AKI in this population of patients is currently underestimated and associated adverse outcomes after AKI are not well understood,” they wrote. “Further work to evaluate the pathogenesis for AKI and the risk factors associated with the increased AKI rate in patients with diabetes, such as use of medication, is required to allow for development and implementation of interventions that both prevent the occurrence of AKI and reduce decline in eGFR, thereby improving patient outcomes.”