Daniel M. Keller, PhD

September 30, 2011

September 30, 2011 (Chicago, Illinois) — In a study of a large population of patients with diabetes, poor short-term glucose control was associated with a significantly elevated risk for bloodstream infection (BSI). Lead author Christie Jeon, ScD, research fellow at the Columbia University School of Nursing in New York City, presented the findings during a poster session here at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy.

However, the researchers report that hypoglycemia and glycated hemoglobin (HbA1c) levels were not associated with the risk for BSI.

Despite a sharp rise in the number of patients with diabetes and impaired glucose tolerance, and the association between these conditions and an elevated risk for BSI, Dr. Jeon's team found that there was limited information on the levels and time frame of glucose control and the levels of risk. They therefore investigated the impact of short-term and long-term glucose control on healthcare-associated BSIs.

Compiling data from the admission records of almost 19,000 patients with diabetes and almost 61,000 patients without diabetes, who had been admitted to hospitals that were part of a large healthcare system in New York City, the investigators recorded the maximum glucose levels for 3 overlapping periods leading up to the date of infection: from the index date and 2 days prior (day 0 to day –2); from day –1 to day –3; and from day –2 to day –4.

Maximum short-term glucose levels were categorized as less than 80 mg/dL, 80 to 109 mg/dL, 110 to 139 mg/dL, 140 to 179 mg/dL,180 to 199 mg/dL, and 200 mg/dL or more. HbA1c levels were used as a measure of long-term glucose control. BSI was confirmed with a positive blood culture with no positive culture of the same organism at other body sites in the 14 days prior to the positive blood culture.

Using multivariate analyses to control for demographic factors, comorbidities, and in-hospital procedures, Dr. Jeon and coworkers found that blood glucose levels of 110 mg/dL or more closest to the index date of infection were associated with BSIs in patients with or without diabetes. However, there was no association with risk when blood glucose levels more than 2 days prior to the index date were considered.

In an earlier multivariate analysis of a smaller sample of diabetic patients (n = 14,913), a short-term blood glucose level of 110 to 139 mg/dL was found to be associated with about a 2-fold increased risk for BSI.

Blood Glucose Level and Risk for BSI in Diabetic Patients

Blood glucose level (mg/dL) Hazard ratio (95% confidence interval)
110 to 139 1.97 (1.02 to 3.80)
180 to 199 2.67 (1.28 to 5.57)
≥200 2.61 (1.32 to 5.15)

Dr. Jeon said that these findings suggest that short-term hyperglycemia is an effect of a BSI, not necessarily a contributing cause of the infection. Clinicians might find a rising blood glucose level to be a useful indicator of a developing BSI in healthcare settings. However, the study did not determine whether better short-term glucose control in hospitalized patients would have an impact on healthcare-associated BSIs.

David Hooper, MD, chief of the infection control unit and associate chief of the infectious disease division at Massachusetts General Hospital in Boston, and president of the American Society of Microbiology, told Medscape Medical News that it is interesting on 2 accounts that long-term glucose control did not correlate with BSI, but that elevated glucose levels within 3 days of the onset of infection did.

"There have been other studies in cardiothoracic surgery in which control of glucose levels around the time of the procedure, hitting certain targets, reduced the risk of surgical site infections," he said. "Another factor in diabetics...is that infections at any number of sites can be associated with worsening control of glucose on the same regimens."

Dr. Hooper also wondered if the very near-term perturbations in blood glucose levels were an indicator that "something was brewing" — it wasn't that the high glucose itself increased the risk for BSIs, it was an early marker of an infection that was detected on blood cultures.

Jesús Rodriguez-Baño, MD, PhD, head of infectious diseases at University Hospital Macarena in Seville, Spain, said that when patients develop an infection, particularly when they are diabetic, it's more difficult to control glucose levels. But "glucose control can also be dangerous when you are trying to be too tight, so you have to be careful with that," he warned.

The research did not receive any commercial funding. Dr. Jeon, Dr. Hooper, and Dr. Rodriguez-Baño have disclosed no relevant financial relationships.

51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract K-829. Presented September 18, 2011.


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