I'd be curious to know if their diabetes was well controlled prior to contracting the corona virus or if it was out of control and already a cause of risk. Did the corona virus _cause_ the problem, or just make it worse?
It seems the above poses another question; is diabetes just confounding other underlying condition(s)?
Further, if most of the patients suffered from type 2 diabetes, it would likely correlate with older age in which case higher fatality rates are to be expected.
I was unable to find this info publicly available, but diabetes being one of the "2+ underlying conditions" seems probable.