What is the target blood glucose for noncritical care patients?
Case
A 65-year-old obese (100 kg) man with type 2 diabetes, hypertension, and a pack-a-day smoking habit is admitted with moderately severe bilobar pneumonia. His condition is manifest by fever, cough, chills, leukocytosis, and a modest oxygen requirement. You order oxygen, intravenous (IV) fluids, diet, and appropriate antibiotics while continuing the history and chart review. The patient uses metformin and glyburide, and his home glucose readings are generally in the 160 to 180 mg/dL range. An HbA1c level performed three months ago was 9.8, leading to an increased dose of glyburide. As you finish the history, the nurse reports a glucose reading of 198 mg/dL. What is the target blood glucose for noncritical care adult inpatients?
Overview
Diabetes mellitus is an epidemic in the United States. At least 9.3% of adults older than 20 (more than 20 million people) have diabetes. Approximately 30% are unaware they have diabetes.1 Concurrent with the increasing prevalence of diabetes in the U.S. from 1980 through 2003, the number of hospital discharges with diabetes as any listed diagnosis more than doubled between 1980 and 2003. These trends are expected to accelerate.2 Studies suggest 26% of inpatients have diabetes and 12% have pre-diabetes, previously undiagnosed diabetes, or stress hyperglycemia.3
Review of the Data
A full review of the evidence is beyond the scope of this article. What follows is a sampling of the most representative or influential critical care studies.
Physiology
Fluid and electrolyte balance, left ventricular (LV) function, leukocyte action, wound healing, endothelial function, and immunoglobulin function are all impaired with hyperglycemia.
A prothrombotic state and enhanced platelet aggregation have been demonstrated with even mild elevations of blood glucose.
The mechanisms are multifactorial and complex and involve metabolic derangements leading to oxidative stress, release of free fatty acids, and counter-regulatory hormones.4-6
Observational Studies
A strong and consistent association with hyperglycemia and adverse outcomes is seen in a wide variety of critical care and peri-operative settings. Trauma survival, stroke survival and function, and the incidence of post-operative infections are all adversely affected by hyperglycemia.7-10 Acute myocardial infarction (MI) mortality, acute MI infarct size, and LV dysfunction are also consistently adversely affected in these studies.11-13
