GLUCOMETER ANALYSIS OF ONE-HOUR GLUCOSE CHALLENGE SAMPLES

OBJECTIVE: Our purpose was to explore a cost-saving measure for diabet es screening by using glucometer testing on venous whole blood obtaine d after a 1-hour glucose challenge test. Glucometer results falling ab ove an upper threshold would predict abnormal plasma values and mandat e a glucose tolerance test; results below the lower threshold would pr edict normal plasma values and avoid further testing. Results between the thresholds would require traditional plasma analysis. STUDY DESIGN : We performed a prospective cohort study on 222 consecutive pregnant women. A standard 50 gm glucose screen was performed with venous blood drawn at 1 hour. We immediately removed a drop of whole blood from th e venous sample and analyzed it on a portable glucometer, AccuChek III . The remaining sample was submitted immediately for routine plasma an alysis. All values were obtained on the same glucometer, which was cal ibrated daily in our clinic laboratory. Regression analysis was perfor med on 129 samples to select the two thresholds. the selected threshol ds were then applied prospectively to the next 93 consecutive samples for validation. RESULTS: Excellent correlation (r = 0.9045) exists bet ween the glucometer and laboratory values. Glucometer threshold values of 110 mg/dl and 155 mg/dl were selected because they predicted plasm a values <135 mg/dl or >135 mg/dl with 95% certainty, respectively. Pr ospectively, the thresholds were completely accurate in classifying th e values. CONCLUSION: Venous whole blood assayed by glucometer can rel iably predict an elevated or normal automated plasma glucose value. By applying thresholds, three fourths of all patients can immediately re ceive reassuring information, whereas the patients with poorest glucos e tolerance are immediately identified and diagnostic testing is sched uled. Additionally, our model reduces the number of automated laborato ry studies by 80% and reduces the cost of diabetic screening.