Us T2s are usually still given advice not to test at all!
However testing is the only way to know how your body responds to the food you have just eaten before you totally forget what you ate.
Since you are trying to control your diabetes through you way of eating (please NOT a 'diet'), your meter is your best advisor.
This is because although all Type 2 diabetics have an intolerance to carbohydrates, the type of carbs and the quantity of carbs we can tolerate reasonably well varies from person to person. Some can eat some oats, some can eat an apple, some can eat a raw carrot - I can't because they spike my blood glucose too high. If it was not for me testing before and after meals until I knew this, I would've had no way of finding it out.
If you are only on Metformin (and not Insulin) then Low Carb High(er) Fat is a good option for you. It is a 'way of eating' not a diet, since the objective is to have as few meals per day with few enough carbs keep a good BG level while never going hungry.
So eat good satisfying meals with lots of protein and plenty of fat so you can last until the next meal without either snacking or suffering ravening hunger.
I'm living proof that Low Carb is a way to control Blood Sugar and to lose weight without calorie restriction or feeling deprived. As are many of Dr David Unwin's patients in the UK, Virta Health's patients in the USA and thousands of users of this site's Low Carb Program.
Never ignore you health care professionals, but weigh the evidence for yourself and trust your meter.