Asthma can be controlled/treated to a level where, asthma exacerbation are reduced and even non triggered. Plus, cleanliness and allergic substances/triggers could be avoided.

Diabetes, moreover, can cause damage to other parts of the body. Kidney, nerves, eyes for example.
Even with treatment, the diabetes could gradually become severe. And the treatment/control pills have to be correctly/timely administered before meals daily.

Plus, you should search and compare the economic cost for treatment diabetic and asthma worldwide.
Diabetes treatment cost more. Its in the billions annually.