Pancreatic diabetes is usually a complication of other pancreatic disorders. Diabetes was a complication in 55.5% of 2,774 patients with chronic pancreatitis (CP) in Japan. More than half of alcoholic patients with CP in our clinic showed diabetes, and -50% of those patients with diabetes were treated with insulin injections. On the other hand, cases of nonalcoholic CP showed mild endocrine dysfunction in terms of diabetic frequency and severity. Epidemiologic studies suggest that diabetes resulting from chronic pancreatitis accounts for <0.8% of all Japanese patients with diabetes. In patients with CP, B-cell dysfunction occurred first, followed by disturbances in A-cell function. Decreased insulin secretion during postprandial periods plays an important role in pancreatic diabetes. The fasting level of blood glucose is not useful for the diagnosis of the early stage of pancreatic diabetes. The glucose-tolerance test should be performed to diagnose early-stage diabetes in patients with CP with normal fasting blood glucose levels. For control of blood glucose in diabetic patients with CP, multiple injections of short-acting effective insulin before the meal are necessary. The incidence of long-term diabetic complications, diabetic retinopathy, nephropathy and neuropathy, in patients with CP with diabetes are not less than those in patients with primary diabetes.