Objective: A patient Web portal allows patients to access their personal health record through the Internet. It may improve diabetes outcomes, but the adoption is unsatisfactory. We examined the differences between patients with and without a login in order to optimize its use. Patients and Methods: A survey was conducted among patients from 62 general practices and one outpatient clinic that all use a diabetes Web portal. Between November 2011 and March 2012 questionnaires were sent to 1,500 patients with and 3,000 patients without a login. Patient groups were stratified according to type of diabetes. Demographic and diabetes-related variables were analyzed with multivariable regression analysis. Results: The total response rate was 67%. Fewer than 50% of the patients did request a login. Among 128 patients with type 1 diabetes mellitus, those with a login (89.8%) were younger and more frequently treated by an internist. In 1,262 patients with type 2 diabetes mellitus, fewer patients had a log-in (41.0%), and the likelihood of having a login was independently associated with younger age, male gender, higher educational level, treatment by an internist, longer duration of diabetes, and polypharmacy (all P<0.001). Conclusions: Patients with type 1 diabetes request a login more frequently than patients with type 2 diabetes, and patients with a login are strikingly different than patients without. The healthcare provider seems to play an important role in patients' Web utilization. Simply promoting use of electronic healthcare methods does not make sense. It is important to address disparities between patient groups to optimize the use of a Web portal.