BACKGROUND To assess whether there are clinically significant problems in patients with insulin-dependent diabetes mellitus (IDDM) traveling to tropical countries regarding metabolic dysregulations, infectious complications and general health problems. METHODS A retrospective, descriptive cohort study by telephone interview of all IDDM patients who had received pretravel health advice at our travel clinic during a 12 month period. Data were collected on IDDM related problems: hypo-/hyperglycemic dysregulation, infectious complications, practical difficulties, exploring risk factors, as well as on general health problems. RESULTS Of the 19 respondents, 13 (68%) reported any metabolic dysregulation, including all but one respondents with Type 1 diabetes. Fifty-five percent of Type 1 diabetics reported to have dysregulated more often than in the preceding period at home. Critical dysregulations occurred in 2 of the 19 study patients. Only 4 out of 11 (36%) type 1 IDDM patients increased frequency of blood glucose monitoring while traveling. Three travelers reported a febrile illness which resulted in hyperglycemic dysregulation. Five study patients experienced difficulties in the adjustment of their insulin dosage to the unfamiliar circumstances of traveling in the tropics. CONCLUSIONS Metabolic dysregulation was a clinically significant problem, thus IDDM travelers to tropical destinations probably run extra health risks. Fever, easily acquired in the tropics, appeared to be an additional, serious health problem for this study population. As the number of diabetic travelers will increase, more research on the importance of risk factors possibly leading to dysregulation is necessary.