Welcome to HCM
like disease at present can not be cured but can be controlled by diet exercises and medications.
260 mg/dl is uncontrolled so he should take his health seriously, do not stop antidiabetic
drugs as it causes blood sugar level to rise to dangerous level.
He should take diabetic diet avoid refind sugars and take up regular walking exercise and gradully can be increased.
As uncontrolled sugar in long term causes many complication on kidney
.heart.Eyes.Keep FBS and PPBS under check and do a HB A1c every 3 months to know control of blood sugar level
Good luck to you