Hi Tazdevl and welcome
The more important test result is the HbA1c. That shows a good indication of your blood glucose levels over the last three months or so, weighted towards recent weeks. Your result of 83mmol/mol is high, but not as high as where many people on these forums began. The 16.2mmol/litre from the fingerprick test shows what your blood glucose was at the moment of the test. It's high too, but fingerprick results can change quickly and in response to things other than food - stress or illness are good examples. One of the issues to be tackled is that your system may be used to living with high blood glucose, and your body will actually be doing its best to keep those levels high. That's a problem because high blood glucose over time will damage nerves and capilliaries, and cause further damage.
My best advice is to try to forget everything you think you know about "healthy eating" - what we've been told since around 1980 or so about fat being bad and carbs being good. Unfortunately the media still churn that out. Many of us here have found that greatly reducing carb, and eating mainly fats and proteins has an immediate impact. In my case I went from diabetic BG levels to normal BG in about four months, and in the couple of years afterwards lost around 90lbs.
No medication. I stopped eating bread, pasta, pastry, cereals, fruit, potatoes, beer and anything sugary. This has worked for many people. We don't all seem to react in exactly the same way to food, so you will need to find out what works for you, rather than following exactly what other people have done.
The key to this is monitoring your blood glucose through fingerprick testing. This will show you how well (or not) your body deals with various foods. The usual pattern is to take a baseline test immediately before you eat, and then a second test two hours later. This is not to see "how high you go" - a high point usually occurs about 45 minutes after eating, for everyone. This shows how well your body dealt with the carb/glucose in the food. The ideal is that by two hours you will be back at or close to the point at which you began - so within 2mmol/l of the first result, and not above 8mmol/l.
If that's the result you get, then you can probably say that your are currently able to handle the carb in what you ate. If not, there's too much carb/glucose in the meal for your system to deal with, and it would be a good idea to reduce the carb level further.
I'd have a good read-around on the forums - the Success Stories section is good. Also, you can ask as many questions as you like. Best of luck.