Try this Quick Fix

Do this with a STRONG WIFI CONNECTION

Within Glucose Buddy App, go to Settings, Account Info, Join Us (pay no attention to the username and password currently entered)

Enter:
First Name
Last Name

Click Next

Email: BRAND NEW EMAIL ADDRESS
Username: BRAND NEW USERNAME
Password: BRAND NEW PASSWORD

Click Next, Select Time Zone, then Join.

Close Glucose Buddy App.

Verify Email sent to you, click the link within Email.

Then close your Internet browser.

Open Glucose Buddy App, tap Settings -> Sync.

Go to https://beta.glucosebuddy.com/login and enter new username information.