Non diabetic levels are between 4 -7 on a fingerprick test but both those numbers are 'ish' so 'high 3s to high 7s' is the general range. The other test - the HbA1c test - is reported in whole numbers, not percentages, non D is below 48, diabetes can only be properly diagnosed from the HbA1c test, and starts at 48 but can easily be 100+. It had used to be expressed as a percentage and still is in America - but if for whatever reason it's been converted to a percentage and the 15.9
was your HbA1c, that converts to 150+ and so I should think you'd have been carted off to A&E in an ambulance and hence don't really think it can be.
Years ago we had used to test our wee by boiling it up in a test tube and seeing what colour it went but since excess glucose doesn't spill over into urine until the blood glucose level is over 11 - by 1980 that method had been scrapped in favour of home blood testing using a meter, being far more accurate. (Those early ones were approx the size of half a housebrick to begin with
😱, but are now one helluva lot smaller!

)
Just for now, let's assume you are really Type 2.
Firstly, do you know which foods generally contain a lot of carbohydrate? Sugar itself is the first candidate, because sugar contains about 100% carb and hence is the very first thing to cut down on pdq. So - that means anything with sugar in it plus anything with ~ose in it be that fructose, sucrose, maltose, dextrose etc. In the UK, it's necessary to read that part on the back of packets and tins, eg on a packet of biscuits it will tell you eg per 100g, 55g carb, per biscuit 7.5g. Yes you already knew biscuits contained sugar, but then there's quite a lot of carb in flour too so you have to add that. So - anything with flour in it eg bread, pastry or pasta, ditto rice, spuds, some fruits - tropical being the most but anything sweet and juicy like pears peaches etc and bananas.
You don't instantly need to give up everything in one fell swoop - but you do need to try and eat less carbohydrate wherever you can cut it down painlessly. Take pies (savoury or sweet) for instance - I enjoy the pastry on the top all nice and crispy, but not the soggy part underneath the filling so am happy to leave the soggy part on the plate to be scraped in the bin. Husband is happy to share an apple, last Sept we were in Normandy and freely confess to scrumping pears on branches hanging over the pavement along roads - not knowing the condition of either the trees or the growing , we automatically cut em in half to make sure they weren't bug infested anyway before risking eating them. See what I mean? It doesn't have to be difficult unless you decide to make it so!