Screening for diabetes is controversial1 and expensive, at an estimated cost of between $176 and $332 per new diabetic patient identified.2 Approximately 40 million anesthetics are performed in the United States per year (http://www.asahq.org/patientEducation.htm). This easily accessible population is potentially available for screening. With the current trend toward cost containment, most patients without a preexisting diagnosis of diabetes do not routinely get a preoperative glucose measurement. In the United States, people 20 yr or older have diabetes and prediabetes at a rate of 12.9% and 25.7%, respectively, and many people are unaware of their disease.3 A cost-effective screening methodology in the preoperative environment might advance diagnosis and effect an overall reduction in total health care costs.
In the perioperative setting, suboptimal glucose control has been shown by some authors to be a risk factor for increased postoperative morbidity and mortality.4–8 Patients with undiagnosed diabetes that has been identified preoperatively may benefit from a routine preoperative blood glucose measurement because they could be alerted to their hyperglycemic condition and long-term diabetes management could be implemented earlier in the course of the disease.
Diabetes screening must be financially acceptable to gain widespread appeal.9 The purpose of this study was to assess a potentially inexpensive, easily implemented diabetes and prediabetes screening methodology for identifying undiagnosed pre- and diabetic patients in the perioperative setting. From the personnel cost viewpoint, we hypothesized that the incremental cost of professional nursing time to measure and record the glucose concentration is negligible.
After IRB approval and informed consent, 347 adult, nonpregnant fasting patients had a preoperative venous whole blood glucose measurement determined. All patients had verification of overnight fasting status and underwent IV catheter placement in the preoperative holding area. A drop of blood residue remaining on the IV catheter needle was sampled to measure the blood glucose with an Accu-Chek Inform glucometer (Roche Diagnostics, Indianapolis, IN). The cost of each glucometer strip at our institution is $0.37. The blood glucose concentration is automatically converted to a plasma-equivalent value by the meter. The patient’s age and any history of diabetes were recorded. In the event of an increased blood glucose level (≥100 mg/dL), the patient was informed, and the appropriate clinical team was notified that a second fasting glucose should be measured to confirm a diagnosis.
A personal communication from a former executive of one of the major diagnostic companies told us their data showed that, in patients with diabetes, it took 60–90 s to perform glucose testing. We performed a discreet event analysis for adding the process of obtaining the blood glucose value at the time of IV catheter insertion, which added 30–90 s to the process of IV insertion. The only extra steps for the nurse were starting the device, placing a strip into the chamber, and recording the glucose value.
Mean residence time for our patients in the preoperative holding area was determined from the Navicare® software system (Batesville, IN) over the time period of the study.
Three hundred forty-seven fasting patients (age range 19–76 yr; 174 men and 155 women) were tested. Eighteen patients (5.1%) were excluded for either a documented history of diabetes or prediabetes in the medical record or if the patient told the physician obtaining informed consent that they had been previously diagnosed with either diabetes or prediabetes. Of the remaining 329 patients, 9 (2.7%; 6 men and 3 women) had a glucose measurement between 100 and 125 mg/dL. Four patients (1.2%; 2 men and 2 women) had a fasting preoperative glucose measurement more than 125 mg/dL (Table 1). The highest glucose recorded was 224 mg/dL in a 42-yr-old man. Glucose measurements are also categorized by age, because there is a steep increase in the incidence of Type 2 disease after 45 yr of age.10
The cost for each newly diagnosed patient with prediabetes was $14.22 ($128/9 patients) and for diabetes was $32.00 ($128/4 patients) with an average of $9.85 ($128/13 patients) per newly diagnosed patient.
The mean residence time of patients in our preoperative holding area was 107 ± 6 min, whereas the additional time for the intervention described herein was approximately 0.5–1.5 min (0.4%–1.4% of total residence time).
With a cost of only $0.37 per testing strip, the total disposable cost for the study was 347 strips × $0.37, or $128. With respect to equipment, the glucometers are donated to the hospital in exchange for the hospital’s purchase of the strips. Therefore, there is no cost for the device included. This represents the costs for our hospital, and it is sensitive to the particular marginal costs for each particular institution. In addition, all nurses working in our holding area must already be trained in the use of glucometers. The cost of this preoperative test per patient identified ($14.22 for prediabetes and $32.00 for diabetes) is approximately one-tenth of the published estimates of the cost of glucose screening, ranging from $176 (single payer perspective) to $332 (societal perspective) per patient identified with previously unsuspected prediabetes or diabetes.2
This study describes and validates an inexpensive and readily implemented screening test for patients with diabetes or prediabetes, easily used in the preoperative setting. The nursing time involved was minimal and was done in parallel with other preoperative activities. Earlier diagnosis of diabetes is certainly not trivial because diabetic complications are developing during this time period.11
There are 3 major limitations of this study. First, there is an inherent inaccuracy of the Accu-Chek Inform compared with central laboratory glucose measurement devices.12 However, Ghys et al.12 reported the predicted bias of the Accu-Chek Inform for a glucose concentration of 7 mmol/L (126 mg/dL) to be only 0.4 mmol/L (7.2 mg/dL). Slater-Maclean et al.13 studied the Accu-Chek Inform and found a mean bias from reference of −0.25 mmol/L (−4.5 mg/dL) at a mean blood glucose concentration of 121 mg/dL. Second, our patients were each tested only once. The American Diabetes Association recommends confirmation of the glucose measurement on a subsequent day.14 Although we did not formally notify subjects of their diabetic or prediabetic status, a number of methods are available to notify them of their condition and that they should get a second test. Third, there is no guarantee that the information will later be communicated to the patient’s primary care provider.
This fasting preoperative blood glucose screening test is another way that our specialty can help to advance the health and perioperative care of our patients. Given that fewer preoperative laboratory tests are now ordered, this offers a way to initiate earlier identification and subsequent intervention in previously undiagnosed patients with prediabetes and diabetes to improve their immediate and long-term care.
The authors thank Dr. Douglas B. Coursin for reviewing the manuscript and making thoughtful suggestions. They also gratefully acknowledge David A. Paulus, MD, for his assistance in obtaining the holding time data.
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