If hyperthyroidism is not controlled for a long time, serious complications will occur. From this perspective, I think it is better to treat hypothyroidism than to control hyperthyroidism. As for why, you can consult a doctor in a local hospital.
Both hypertension and hypoglycemia you mentioned may be caused by hyperthyroidism, so the first thing you should consider is to completely control hyperthyroidism.
I would like to remind you that hyperthyroidism is a common clinical disease, which can be treated in general hospitals, especially in top three hospitals. Don't believe those advertisements of unknown origin, which sound very attractive and can capture the patient's eagerness to seek medical treatment, but they are actually cheating money.