Autoimmune pancreatitis (AIP) is a distinctive type of pancreatitis, and it is thought that the pathogenesis of AIP involves autoimmune mechanisms.1–6 Recently AIP has been regarded as a systemic disease because it is often accompanied by various extrapancreatic lesions including cholangitis, sialadenitis, retroperitoneal fibrosis, hilar lymphadenopathy and chronic thyroiditis.7–10 Furthermore, AIP is often associated with pancreatic exocrine and endocrine dysfunction. Pancreatic exocrine dysfunction is reported in 83%–88% of AIP cases and diabetes mellitus (DM) in 42%–78%.10–14 However, very few reports have been published on AIP-associated pancreatic diabetes and its pathophysiology, complications and treatment have not been investigated at all. We recently examined the epidemiology of pancreatic diabetes in Japan in 2005 using a nationwide stratified random sampling method.15 In this report, no analysis of AIP-associated pancreatic diabetes was included. Accordingly, in the current study we selected AIP patients from the pancreatic diabetes patients surveyed and conducted a detailed analysis of the pathophysiology, complications and treatment of AIP-associated pancreatic diabetes.