Andy,
You should know that grease, fats and oils have absolutely nothing to do with diabetes. There are a number of cookware items on the market that allow you to cook without additional fat or oils (e.g. grills produced under the name of a former heavyweight boxer).
Any publicity that tells you that using this cookware can reduce or stop reliance on insulin by a diabetic is simply telling you a pack of lies and, if sold in the UK, should be reported immediately to your local Trading Standards Office.