but there's an impact if you are being sponsored. It clearly states to cic website that she/he must be healthy. For trv application you need to proved that the health condition is stable and well maintained. In addition to travel insurance.
It should not be a problem, unless there is a heart issue too. Usually, people are allowed to visit Canada with such medical conditions, provided that your family doctor or physician has given an approval (does not have to be formal) your trip.
There is a different story with a health insurance for Visitors to Canada (TRV, Super Visa (PG-1), etc). Both diabetes and high/low blood pressure are considered pre-existing medical conditions, and if you want to get them covered, these conditions have to be stable for at least 120 to 180 days.
No, it won't be a problem for Super Visa eligibility. The only thing is that, if something happens resulting from these pre-existing conditions, it will not be covered under the insurance policy.