Hello, Invokana (Canaglifozin) is a new medication which promotes excretion of glucose through the urine by decreasing its reabsorption. There is no known interaction with the other medicines he is on. But as you very rightly pointed out, does he require all these medicines especially since you noticed that his blood sugar was down when he was off the medicines? This raises an interesting possibility. There is a condition called Somogyi effect in which blood sugar goes below normal making the body take corrective measures by secreting hormones that elevate the blood sugar often leading to a higher than normal blood sugar. As you might know a proper low Glycemic Index (GI) diet, exercise, weight reduction if overweight and stress management are very important and those who practise these are able to control their blood glucose with less medicines in my experience. So if he is not practising these, why not give it a try? I hope he is monitoring his blood sugars at home with a glucometer. I shall be glad to be of help if you have further queries. Do let me know the progress in a couple of weeks. Best wishes, Dr. Noble Zachariah M.D.