Swelling in legs, ankles and feet is common in diabetes which is often caused by water retention. Good blood glucose control, low dietary salt intake, elevation of your feet and wearing support stockings as well as exercise help to alleviate swelling. Call your doctor as soon as possible if swelling does not improve or worsens or if you have also liver disease and experience swelling in your legs or abdomen, if you have fever or noticed decreased urine output.