You can increase your walking to one hour. Also walk like you mean it, do not stroll. Most important is to control and manage your diabetes. Then limit your carbohydrate food intake for weight loss. Use Google to search and understand the difference between 'simple carbs and complex carbs'. Go to the Atkins web site for low carb information and recipes. Click on programs to get started. http://atkins.com/Homepage.aspx
Pay careful attention to your breath, your body odor, or urine if any starts to have a fruity sweet smell. This is the beginning of ketosis caused by the body switching from burning carbohydrates to only fat. It is telling you that your carb intake is way too low. Ketosis can be hard on your kidneys so don't eliminate carbs altogether. Good luck
By eating less carbohydrates you will need less insulin. If you need less insulin to maintain excellent blood sugars then you will slowly get to your optimum weight. If you are serious about this I can strongly recommend the book "diabetes solution" by Dr. Richard Bernstein, you can google this. His book explains how to safely use insulin and diet to manage blood sugars and weight. His approach is similar to Atkins, but is more finely tuned to suit people with diabetes (both types 1 and 2, insulin and non-insulin dependent).
Of course exercise is also very important.
You will need to monitor your blood sugars and response to insulin carefully.