Insulin Therapy Protects Renal Function in Critical Patients

The study sample consisted of 2707 critically ill patients who were randomized to receive conventional insulin therapy or IIT. The researchers excluded 41 patients with preadmission end-stage renal disease (ESRD). Acute kidney injury was classified with a modified risk-injury-failure-loss-ESRD (mRIFLE) system, so that mRIFLE-Injury (mR-I) and mRIFLE-Failure (mR-IF) corresponded to peak serum-creatinine levels 2 or more and 3 or more times the admission levels, respectively.

The researchers found that IIT was associated with a decreased incidence of mR-I or mR-F from 7.6% to 4.5%. This protective effect on renal function was most dramatic in patients who achieved strict normoglycemia. In surgical patients, IIT was also associated with decreased incidence of oliguria, and of the need for renal replacement therapy. The incidence of mR-I or mR-F decreased to a lesser extent in medical patients. The study authors attributed this to a greater severity of illness at admission, which could have lowered the efficacy of preventive treatment. The study was published online in the January 30, 2008, issue of the Journal of the American Society of Nephrology (JASN).

"Several large clinical trials have shown that strict blood glucose control in both type 1 and type 2 diabetes has a beneficial effect on the development and progression of diabetic nephropathy,” concluded lead author Miet Schetz, M.D., and colleagues. "Hyperglycemia and insulin resistance are also common in critically ill patients, even in those without diabetes, and are associated with increased morbidity and mortality.”

Acute kidney injury (AKI) may be present in up to one quarter of patients in the ICU and even mild increases in the level of serum creatinine can portend a worse mortality prognosis. Additionally, hyperglycemia has been demonstrated to increase the risk for AKI after cardiac surgery, and can also increase the risk of developing contrast nephropathy. Changes in the serum lipid profile and serum levels of nitric oxide (NO) have also been implicated in promoting acute kidney injury among patients who are critically ill. IIT promoted higher levels of both low-density and high-density lipoprotein cholesterol as well as reduced NO levels versus control treatment, suggesting possible mechanisms for its efficacy.


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