I've been taking creatine in 12 week cycles on and off for years now and never had problems. Keeping in mind that other then diabetes i'm healthy. Furthermore according to examine.com creatine has very little influence on blood pressure with 4 studies that confirm these findings. Caution is off course always merited when making any significant dietary chances. Personally i would already consider not taking it with hypertension since as i will often mention in the next paragraphs creatine barely does a thing.
Keep in mind that creatine does nothing to help endurance sports, not even a little bit but nothing. It's only relevant in the ATP-ADP cycle and that depletes in the blink of an eye sort of speak. It's is however a class A supplements meaning that it's effects have been proven over and over again. If your diet is on the level you could take creatine to ever so slightly increase your performance in the gym, however if you can make improvements in your general diet i'd start there since there is much more potential for overall benefit in athletic performance and diabetic control. Personally i find that when entering high intensity weeks (high weight loads +85% of max) i'd rather be taking it than not, i notice a slight difference on the last reps. However it's not like i can't lift the weight if the cycle ends (not taking it for a week) during one of those high intensity weeks, it's just a matter of fatigue. Honestly the reason i take it is because i'm competitive (mostly with myself lately) and i feel like i'm nearing my physical limits so every bit helps. But it's your choice whether you want to spend the money on something that honestly only helps a little.
Another general remark is that loading phases like often suggested have never been found to benefit the user, only the seller of the product since the jar is empty faster.
If you want something that will help your endurance performance and also helps in the gym: nitrate supplementation. Which as an added benefit for you shows effects to lower blood pressure. It lowers the oxygen cost in aerobic exercises and increases performance. Again it helps a bit but it does help. Most people take it in the form of a beet juice but that contains a good amount of carbs.