Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis (CP), which displays clinical, morphological, serological, radiological and in particular histological features that are distinct from those of other types of CP. CP can cause pancreatic diabetes mellitus (DM). The pathomechanism and clinical features of pancreatic DM differ from those of types 1 and 2 DM, and the principles of its treatment may also differ. Our aims were to assess the characteristics of AIP cases in Hungary; to assess the presence of AIP in various systemic autoimmune diseases (SAIDs) and to evaluate the effectivity of insulin therapy in patients with pancreatic DM. The presented three clinical studies have demonstrated that AIP is present and increasingly recognized in the Hungarian population. Our second study allowed the conclusion that the serum IgG4 level may be elevated in SAIDs, but as a consequence of the concomitant SAID rather than of AIP. The determina¬tion of serum IgG4 does not seem to be suitable for the differentiation between IgG4-related diseases and SAIDs. The third study suggested that oral medication may become insufficient early in pancreatic DM.