Aim To determine the prevalence and risk factors of new-onset diabetes mellitus in patients after a first episode of acute pancreatitis. Methods A retrospective study design was used. Patients diagnosed with a first episode of acute pancreatitis in the emergency department of a tertiary medical center in 2010-2016 were followed for the occurrence of diabetes mellitus. Clinical data were collected from the medical records and compared between patients with and without a subsequent diagnosis of diabetes. Results Of 500 patients who presented with a first episode of acute pancreatitis during the study period, 41 (8.2%) were subsequently diagnosed with diabetes and 29 (5.6%), with pre-diabetes, and 312 (62.4%) had normal glucose levels; the remainder had pre-existing diabetes. Mean duration of follow-up was 6.7±3.1 years, and mean interval between diagnoses was 1.46±1.4 years. Compared to the patients with normal glucose levels, the diabetes group was characterized by older age (64±17 years vs. 54±21 years, p<0.01) and higher blood pressure values (systolic: 147±21 mmHg vs.131±23 mmHg, p<0.01; diastolic: 83±15 mmHg vs.74±13 mmHg, p=0.013) at presentation to the emergency department, higher score on the Bedside Index for Severity in Acute Pancreatitis (BISAP; 1.22±0.85 vs. 0.88±0.87, p=0.02), and higher rate of non-biliary pancreatitis (45% vs. 26.8%, p=0.02). Conclusions Risk factors for the development of diabetes after a first episode of acute pancreatitis include high blood pressure, high BISAP score, and non-biliary etiology. These findings in patients who present to the emergency department with acute pancreatitis should alert the clinician to the need for close monitoring for diabetes.