I adopted a low GI type diet when I thought I had T2 diabetes (sort of self diagnosed long story and have written it here too many times). This must have been effective for three years since my HbA1c wasn't that high when I was diagnosed with T1 (or LADA, it's slower developing version)
Basically, I chose starchy carbs that were lower on the glycemic index, smaller portions of protein, lots of vegetable and some lower GI fruit. I was already eating a couple of non meat main meals a week. I was careful not to use too much fat/oil in cooking but still ate butter and cheese in small amounts (I continue this).
I ate and still eat porridge for breakfast; even then without a meter, if I tried to eat croissants and strawberry jam for breakfast then I felt unwell.
I continued with this diet when diagnosed but it has gradually morphed into a bit more SW French/Med diet as outlined here I think that the exercise part of the pyramid is really important.
http://oldwayspt.org/resources/heritage-pyramids/mediterranean-pyramid/overview
The SW France bit is probably a bit more meat than a Med diet and includes duck which is fortunately high in monounsaturated fat but a typical portion would be half a breast or a leg so not huge.
I probably eat more potatoes than is normal in this area but less bread (normally small waxy type) with meals but have introduced quinoa, bulghur, green lentils, and barley along with rice (usually a mixture of wild/brown/basmati) and wholegrain pasta
The bread I eat is either seeded, nut bread or local sourdough pain de champagne (not baguette which is very high GI)
I very rarely eat anything but fruit for dessert unless I go out to eat or we have visitors . I no longer cook them then either , why would I when one can buy beautiful patisseries from several shops in town? They normally have far less sugar than British cakes and puddings.
(actually I ordered a dessert the other day as it was part of the prix fixe menu, it was Tiramisiu which I used to like. I had two mouthfuls, and that was far too sweet and 'not worth the insulin')
I eat three meals a day, no snacks in between. I sometimes eat the main meal at lunchtime which is what my diabetologist would prefer; it's the norm here. When I do this I find I am far less likely to see a rise in levels overnight.
My basic plate at main meals is half veg,1/4 meat/fish, 1/4 starch (ie bread/potato/cereal/legume) In addition, I eat some dairy(yoghurt or cheese). I tend to use 0% plain yoghurt or fromage blanc made with skimmed milk but choose good cheese in small portions with some fresh fruit . I have salad at least once a day and use an olive oil vinaigrette.
My breakfast normally contains 38g oats made to 260g with semiskimmed milk with berries (often frozen as cheaper) and slivered almonds
I stayed normal weight for several years after diagnosis but last year was less active , put on weight and was diagnosed with hypothyroid.
I am now more active again, and am paying more attention to calories. ( I use a vivofit fitness band and this synchs to MFP to measure walking type activity during the day)
Calorie wise my basic level to lose is about 1200 (if I am sedentary). On some days I may actually use 2000 calories a day with walking/gardening , others less etc. Most days I eat between 1400 and 1600 and have been losing about 0.5 kg a week (which is about the right rate of loss when you haven't too much to lose)
you can scan bar codes and it has a big database of food and corresponding calories 
It is very easy to add a bit extra here and there.