I'm afraid that the idea that type two diabetes is caused by overeating is firmly entrenched in the thinking of many people - but as you have discovered, fewer calories is not the answer.
Diabetes is an inability to cope with the carbohydrate (the sugar and starch) in the modern diet. The answer is to reduce the heavy starchy foods as much as possible, avoid sugar and select only the lowest carb berries (not blue berries, they are naturally high) and then eat meat fish eggs cheese shellfish, as they are just about carb fee, along with salad and low carb veges, full fat yohurt if you like it, put cream in your coffee and on the fruit.
Blood Glucose levels usually drop very quickly - so fast that those on glucose lowering medication have to be cautious or risk hypos.