While taking medicines, is 150 a high reading for diabetes?

No: That is not a bad reading but was it fasting. If so check 2 hours after a meal and see what you get.

It depends: The ideal blood sugar reading for a person with diabetes varies by age of the person, by time of day, and by circumstance. A blood sugar of 150 might be considered high if it is a first morning fasting blood sugar, but it might be perfect or even a little low for someone with diabetes going into playing a sporting event. 150 is even a normal blood sugar after eating in someone who does not have diabetes.

Depends: Fasting, then yes. Less than a couple of hours following a meal, then it's not really interpretable and should be checked 2 hours following a meal. If a couple of hours after a meal, then this is still a bit on the high side, but pretty good nonetheless.