You're right. But they explicitly wrote "we examined the potential of FUS as a treatment for diabetes". So they are discussing a treatment, not just symptom relief
"Medical treatment" definitely doesn't always mean dealing with the root cause. As you've learned.
Splinting a leg is treatment, but it has nothing to do with not drinking before driving.
Are you confusing the term "treatment" for the term "cure"? Symptom relief is a type of treatment.