Clinical question: Does the use of sliding-scale insulin improve blood glucose control in hospitalized patients?
Bottom line: Sliding-scale insulin is commonly used to manage hyperglycemia in hospitalized patients. The evidence suggests that this regimen does not result in better blood glucose control. (LOE = 1a-)
Reference: Lee Y, Lin Y, Leu W et al. Sliding-scale insulin used for blood glucose control: a meta-analysis of randomized controlled trials. Metabolism 2015;64:1183-1192.
Study design: Meta-analysis (randomized controlled trials)
Funding source: Government
Setting: Inpatient (any location)
Synopsis: These investigators searched multiple databases including PubMed, EMBASE, and the Cochrane Library to find randomized controlled trials that evaluated the efficacy of sliding-scale insulin to manage hyperglycemia in hospitalized patients. Two authors independently evaluated the studies for inclusion, extracted the data, and performed quality assessments.
Eight of the 11 included studies compared regular insulin sliding scale (RISS) regimens with non–sliding-scale regimens. All RISS regimens consisted of subcutaneous regular insulin injections according to patients' blood glucose levels. Non–sliding-scale regimens consisted of basal-bolus or basal insulin regimens, continuous intravenous insulin infusions, and closed-loop artificial pancreas systems. Target blood glucose levels for individual studies varied greatly and included a range of 100 mg/dL to 150 mg/dL, a goal of less than 140 mg/dL, and a goal of less than 180 mg/dL. Hypoglycemia was generally defined as a glucose level of less than 70 mg/dL, though three of the studies had an even lower cut-off.
In the two studies that evaluated hyperglycemia, one defined it as a glucose level greater than 180 mg/dL while the other defined it as greater than 240 mg/dL. A meta-analysis of relevant data showed no significant difference in the percentage of patients who achieved an average blood glucose level in the target range when comparing RISS with non–sliding-scale regimens. The trend, however, favored the non–sliding-scale group and the difference became significant (relative risk 1.48, 95% CI 1.09-2.02) after one study with a very wide confidence interval was removed. Furthermore, the incidence of hyperglycemia and the mean blood glucose levels were significantly higher in the RISS group.
Although overall hypoglycemic episodes occurred more frequently in the non–sliding-scale group, there was no significant difference detected in the incidence of severe or symptomatic hypoglycemia. Length of hospital stay was also similar in both groups. Finally, one study compared the use of routine diabetes medications plus RISS with routine diabetes medications alone and found no difference in the number of hypoglycemic or hyperglycemic events.
Significant heterogeneity was detected in the results of this meta-analysis and can be attributed to the differing patient populations, insulin regimens, and working definitions in the individual studies as noted above.
Dr. Kulkarni is an assistant professor of hospital medicine at Northwestern University in Chicago.