Welcome to HCM
Your father is diabetic, long standing diabetes
reduces immunity and bone TB is something needs a long term treatment that is more thand 1 year with anti tubercular drugs,these drugs cause some changes in liver
function which may be cause of change in control of blood sugar, also as he is taking oral hypoglycemic drugs there may be some insuin resistance and drug failure .
Please consult a Physician /Endocrinologist
and adjust the dose of anti diabetic drugs where Insulin
can be added to your anti diabetic therapy.
Kindly also check Liver function to know any derrangement because of anti tubercular drugs.
Good luck to him.