Future learn will be running a free educational course on "The Diabetes Epidemic" in September. The course is actually being offered by the University of Dundee.
I have done other courses through Future learn and have gained some great knowledge and insights.
The OU do free short taster courses under the OpenLearn banner. I have just completed Living with Diabetes and Diabetes Complications. I found them both interesting and informative and both can be done in a day each. Saving the transcripts provides a good reference.