Background: There has been increasing interest in the use of web portals by patients with type 2 diabetes mellitus (T2DM). Studies of web portal use by patients with pre-diabetes have not been reported. To plan studies of web portal use by adult clinic patients seen for pre-diabetes and T2DM at an academic medical center, we examined characteristics of those who had or had not registered for a web portal. Methods: Electronic records were reviewed to identify web portal registration by patients treated for pre-diabetes or T2DM by age, sex, race and ethnicity. Results: A total of 866 patients with pre-diabetes and 2,376 patients with T2DM were seen in a family medicine outpatient clinic. About 41.5% of patients with pre-diabetes and 34.7% of those with T2DM had registered for the web portal. In logistic regression analysis, web portal registration among patients with T2DM was significantly associated with age 41-45 years, and with Hispanic ethnicity. Similar results were obtained for pre-diabetes except that the positive association with age 41-45 years and inverse association with Hispanic ethnicity were not statistically significant. Among patients with pre-diabetes or T2DM, Black men and Black women were less likely to have registered than their white counterparts. Patients who were aged 18-25 and >65 years were less likely to have registered for the web portal than those 26-65 years. Conclusions: Additional research is needed to identify portal design features that improve health outcomes for patients with pre-diabetes and T2DM and interventions that will increase use of patient portals by pre-diabetic and diabetic patients, especially among Black patients and older patients.