Depression is VERY common in Type 2 diabetes, my A1c levels were initially 12.5% and have never went below 10% and I wouldn't exactly say I'm that overweight either. Sometimes it's the luck of the draw and can be hereditary too so don't be too hard on yourself too. Making good lifestyle choices will improve your health and lifespan, bit of weight loss, exercise, good healthy meals and monitoring your blood pressure will help greatly. A1c levels so high made me feel very tired, fatigued and in that state it is hard to motivate yourself to do anything constructive but since being on insulin I've felt miles better so have faith and try making small changes, one thing at a time and scale up. All the best and good luck mate !