The serum values of para-amino-benzoic acid in subjects affected by type II diabetes mellitus, were measured hourly for 6 hours, after oral ingestion of B-T-PABA. These values were compared with those of a control group. The results demonstrate that at 1, 2, 4 and 5 hours, the mean values of the two groups were significantly different: p less than 0.01, p less than 0.002, p less than 0.0001 and p less than 0.005 respectively. Comparing the area under the curve the data did not differ significantly, indicating that at the end of the sixth hours the quantity of PABA absorbed is very similar in the two groups. These results indicate that patients with diabetes seem to have an altered exocrine pancreatic function, which may be due to a reduction in the zymogen stocked in the acinar cells or a lower secretory response to physiological stimulus. This impairment does not affect the digestion and the nutritional state of the patients.