The purpose of this study is to assess the severity and frequency of gastroesophageal reflux disease in patients with Type 2 Diabetes Mellitus and to evaluate some factors that are thought to be associated with Gastroesophageal Reflux Disease (GERD). The study was a cross-sectional study on individuals aged 18 years and over who applied to outpatient clinics in the Department of Family Medicine and Internal Medicine, Eski?ehir Osmangazi University Medical Faculty Hospital between 1 January and 31 July 2016. In the study, information from 436 individuals using face-to-face interviews and laboratory values (fasting blood sugar and HbA1C) of individuals within the last three months was recorded on questionnaire forms. In the study, the National Institutes of Health Promis Gastroesophageal Reflux Disease Scale was used in the evaluation of GERD. The data were analyzed in the IBM SPSS (version 20.0) statistical package program. Chi-square test and logistic regression Backward: Wald method was used for variables. The statistical significance was accepted as p ≤ 0.05. Among the patients with diabetes mellitus (DM), 134 patients (68.0%) had gastroesophageal reflux disease. 105 diabetic patients (53.3%) had obesity, 146 diabetic patients (74.1%) had high HbA1C levels and 84 diabetic patients (42.6%) had wider waist circumference. The most common treatment modalities for individuals with DM in the study group were oral antidiabetic treatment with a ratio of 65.5% (n=129). The most common gastroesophageal reflux disease severity in the DM group was the most symptomatic (67.2%). The purpose of this study is to investigate the incidence, frequency, and severity of gastroesophageal reflux disease in patients with Type 2 DM using the National Institutes of Health (NIH) Patient- Reported Outcomes Measurement Information System (PROMIS®) Gastroesophageal Reflux Disease (GERD) Scale. Thus helping early diagnosis and treatment of gastrointestinal complications that may occur in association with Type 2 DM.