68 year, Male taking Glucophage 500mg twice daily, now having prediabetic level of fasting plasma level at 115-120mg/dl with normal post-parendial glucose level. Subject having thyroidactomy 9 years before and taking Thyroxin 100mg OD. Also having hypertension and taking Renitec 5mg OD with the normal BP at 120/75 mm of Hg. Should this subject be taking basal insulin or change the medication for treating prediabetes?