Comparison of BT-PABA test and fecal chymotrypsin measurements in normal subjects and diabetic patients

Summary A N-benzoil-L-tyrosil-PABA test on 6h urine collection, a plasma PABA assay 2h after administration and a fecal chymotrypsin assay were performed on 66 patients (36 controls and 30 type 2 diabetic patients on insulin therapy). All patients were hospitalized and without gastrointestinal and renal disease. The mean values of plasmatic PABA and fecal chymotrypsin were significantly lower in the diabetic group than in the controls (p<0.025 and p<0.01, respectively), although they remained within normal range. But this was not the case for PABA urinary excretion values. This may indicate a slower but more protracted PABA absorption during the third or fourth hour with the result that urinary excretion over 6h is not greatly affected. There was good correlation between fecal chymotrypsin values and both PABA urinary excretion values and serum PABA values, a trend observed both in diabetics (p<0.005 and p<0.001, respectively) and in controls (p<0.001 and p<0.005, respectively). This could indicate that even at lower mean levels, the diabetic patients show the same behavior pattern and therefore maintain the same indexes of correlation as the control population. Our results suggest that these indirect, but simple, economical and well-tolerated tests could be considered a valid alternative for investigating pancreatic function especially in those patients that cannot be tested by a Secretin-Cerulein test.