Hi and welcome.
Great that you have a BG meter to test at home. Whilst 17 is higher than you would like, it is not what we would consider needed emergency treatment. Hight 20s or 30s and not coming down would be the time to seek urgent medical help.
Are you on any medication and what if any dietary changes have you made?
When did you take these readings.... ie before food or after and if after how long after and what did you eat?
The best thing that you can do to bring them down is to go for a walk if you are able or other steady (not exertive) exercise and drink plenty of water as your kidneys will help to remove glucose from your blood at that level via your urine, so if you drink plenty of water that will help to flush it out of your system.
After that, depending upon the medication you have been given, reducing the amount of glucose you put into your blood will help to prevent it going that high in the first place. That doesn't mean just cutting down on sugar but all carbohydrates like bread, pasta, rice, breakfast cereals and potatoes etc as well as the obvious cakes and biscuits and sweets. Carbohydrates (sugars and starches) are just chains of glucose molecules and the body breaks them down in your digestive system into glucose, which is absorbed into the blood stream to provide energy for the cells of the body, but being diabetic means that your cells can't access that glucose as efficiently as it used to, so it builds up in the blood stream and creates problems. Reducing the amount of glucose by eating less carbs enables your body to cope with the backlogin your blood and exercise like walking will mean that the cells in your muscles will be using up their stores and will suck some of that excess out of your blood. That is a very simplified version but I think of it a bit like a production line where the product is coming along a conveyor and into the packing area, but there are staff shortages due to illness so the product starts piling up in the packing area and the more that comes off the conveyor the more difficult it is for the packers to do their job as they have no space to work and are tripping over it. If you slow the production line down (less carbs in your diet) and allow the delivery staff to help out with the packing (ie exercising your muscles so that they help to remove some) the system can get back to working more smoothly.
Hope my silly analogy helps makes a bit sense of the problem.