Objectives: The Maastricht III Consensus agreed that effective treatment for Helicobacter pylori (HP) should achieve an intention-to-treat (ITT) eradication rate above 80%, which is still lacking in patients with type 2 diabetes mellitus (DM). This pilot study was designed to confirm the efficacy of a 14-day sequential treatment regimen in patients with type 2 DM. Methods: This is a prospective, open-label, single-center pilot study. All patients included in this study underwent upper gastrointestinal endoscopy. HP status was evaluated in each patient by a rapid urease test and histopathologic examination. For seven days, all patients received pantoprazole 40 mg twice daily (b.i.d.) and amoxicillin 1000 mg b.i.d., followed by pantoprazole 40 mg b.i.d., metronidazole 500 mg b.i.d., and tetracycline 500 mg once each day for the remaining seven days. The study population consisted of 38 consecutive patients with type 2 DM (18 female, 20 male; mean age 48.0 +/- 12.2 years), 30 of whom had non-ulcer dyspepsia, four had gastritis, one had gastric ulcer, and three had duodenal ulcer disease. Eradication was defined as the absence of HP as assessed with the 14C-urea breath test. Results: Thirty-seven of 38 patients completed the study. All side effects were observed in eight patients (21.1%). None of the patients discontinued treatment because of side effects. The eradication rate in the DM group was 22/38 (57.9%) for the ITT analysis and 22/37 (59.5%) for the per-protocol (PP) analysis. Conclusion: The results of 14-day sequential therapy for the first-line treatment of HP in patients with type 2 DM were disappointing. Further studies with new antibiotic combinations are needed to find better methods of eradicating HP in patients with type 2 DM.