yes it is reversible. What you need to do is weight loss (slow and steady), daily exercise at least 30 minutes and some of this should be intense, low carb diet. Avoid all sugars, limit grains, and fruits. Nonstarchy veges and proteins are your new best friends, vegetable frutis such as egg plant, capsicum, avocado are all good. Unsweetened diary, eggs, nuts, etc.
You could follow a paleo or primal way of eating.