USE OF GLUCOSE DISAPPEARANCE RATES (K(G)) TO MONITOR ENDOCRINE FUNCTION OF PANCREAS ALLOGRAFTS

We have reported that a decline in glucose disappearance rate (k(G)) i n pancreas transplant recipients is associated with pancreatic rejecti on, The purpose of this study was to determine test-retest reliability of k(G) monitoring and to establish the k(G) criteria for diagnosing abnormal graft function. Six healthy non-diabetic volunteers and 14 st able pancreas recipients underwent 2 intravenous glucose tolerance tes ts 7 d apart. All k(G) values in non-diabetic volunteers had < 15% var iation between the two determinations (r = 0.96, P less than or equal to 0.0006), Similarly, 13/14 recipients experienced < 20% variation in k(G) with one patients experiencing a 23% variation (r = 0.90, P less than or equal to 0.0001). Using a 20% change from baseline as the ref erence value, we monitored 28 pancreas recipients for 2-36 months post -transplant. Of 253 k(G) values, 160 (64%) did not exceed the 20% chan ge from baseline, 65 (26%) declined > 20% and 28 (11%) increased > 20% . Of 160 stable k(G) values, 154 (96%) were associated with normal gra ft function while 6 (4%) occurred in the context of rejection. Of 65 k (G) values declining by greater than or equal to 20%, 47 (72%) accurat ely identified acute rejections diagnosed by biopsy (70%) or response to treatment (30%), 12 (19%) were associated with identifiable causes of increased insulin resistance and only in 6 (9%) cases a cause for t he decline was unidentifiable. The k(G) values with > 20% rise from ba seline were, in 15%, associated with identifiable causes of decreased insulin resistance. The sensitivity of the k(G) as a marker for reject ion was 88.7%, specificity 91%, positive predictive value 72.3%, negat ive predictive value 96.8%, and accuracy 90.5%, These data confirm tha t a > 20% deterioration of glucose disappearance rate is associated wi th pancreas allograft rejection, and confirms the utility of k(G) moni toring in clinical follow-up of pancreas transplant recipients.