It depends up on what treatment he is on for his diabetes. If he is just taking tablets and not insulin, all he would need is HBA1c level. It tells how well controlled his diabetes is. There is no point in getting fasting and PLBS, but you can still do it if you wish to , but the treatment changes will be based on his HBA1c levels. If he hasn't had any other tests in the past year, I would also recommend getting his CBP, renal profile including urinary albumin creatine ratio, lipid profile and LFTs , etc