Insulin therapy and acute kidney injury in critically ill patients - a systematic review

Background. Intensive insulin therapy has been found to reduce mortality in some critically ill patients. We performed a systematic review and meta-analysis to ascertain the effect of intensive insulin therapy on the incidence of acute kidney injury (AKI) in adult critically ill patients. Methods. We searched MEDLINE, SCOPUS and the Cochrane Central Register of Controlled Trials for studies that compared 'conventional' vs 'intensive' insulin therapy in critically ill patients. Studies were combined with random effects model meta-analyses. Results. Five studies, three of which were randomized controlled trials, reported AKI as a secondary outcome. Two of the studies were non-concurrent prospective cohort studies. All were single-centre studies conducted in intensive care unit settings. By meta-analysis across all studies, intensive insulin therapy reduced the incidence of AKI by 38% [risk ratio (RR) 0.62; 95% confidence interval (CI) 0.47, 0.83; P = 0.001]. The findings of the randomized and cohort studies were similar and the studies were not statistically heterogeneous. Three studies reported the effect of insulin therapy on dialysis requirement. Overall, intensive insulin therapy reduced the incidence of dialysis requirement by 35%, however, this was not statistically significant (RR 0.65; 95% CI 0.40, 1.05; P = 0.08). The overall rate of hypoglycaemia in the conventional insulin therapy group was 1.3% ( range 0.3 - 3.4%). Intensive insulin therapy was associated with a > 4-fold increase in the risk of hypoglycaemia (RR 4.5; 95% CI 2.4, 8.5; P < 0.00001) Conclusion. There is evidence that intensive insulin therapy initiated in critically ill adult patients is associated with a reduction in the incidence of AKI in medical and surgical settings. A large trial primarily designed to examine the effect of insulin on the prevention of AKI is needed to confirm this finding.