Background: Patients with diabetes mellitus (DM) are more likely to have gastroesophageal reflux disease (GERD), and there is a significant association between the two conditions.  A variety of tools, including endoscopy, pH monitoring, and proton pump inhibitor (PPI) test, are available for the diagnosis of GERD. GERD is very prevalent among the majority of people; thus it is highly appealing to apply low-cost, simple methods for identifying high-risk people who might be suffering from it.   Aim: To assess the diagnostic usefulness of the Carlsson-Dent (CD) questionnaire and the frequency scale for detecting the symptoms of the gastroesophageal reflux disease (FSSG) questionnaire as a self-assessment diagnostic instrument in diabetic patients and its relationship with diabetes complications. Patients and methods: This cross-sectional study included 217 adult diabetic patients; 153 females, 64 males who were enrolled in two Endocrinology clinics; the Cairo University hospitals and Beni-Sweif University hospitals from June 2023 to December 2023. All patients were subjected to both CD and FSSG questionnaires (CDQ & FSSGQ respectively). Relevant clinical and laboratory data were gathered such as body mass index (BMI), diabetes control, other comorbidities, added to abdominal ultrasonography. Results: Using the CD questionnaire, GERD was reported in 66% of the study population versus a prevalence of 53% with the FSSGQ. There was a significant agreement between the two questionnaires: of 81.6%, p <0.0001. The presence of hypertension and liver steatosis were significantly associated with GERD diagnosis by the CDQ (P-value 0.03 and 0.004 respectively) and FSSGQ (P-value 0.01 for both). Additionally, NSAID intake, as well as peripheral neuropathy, were associated with GERD using the CDQ (P-value 0.03 and 0.004 respectively). Dyslipidemia was associated with GERD using the FSSGQ (P-value 0.008). Conclusion: A relatively high incidence of GERD symptoms in diabetic patients was observed. There was a significant agreement between the CD and FSSG questionnaires. Hypertension, liver steatosis, dyslipidemia, peripheral neuropathy, and NSAID intake were associated with GERD in diabetics.