A high blood glucose level combined with reduced blood supply to your limbs has the potential to cause nerve damage, reducing feeling in the feet. This can become problematic for those who may not realize that they are developing sores or wearing poorly fitting shoes. In extreme cases, avoiding foot care may result in ulcers which, left unchecked, could require amputation. As a best practice, check your feet every day for any sores, infections, and other ailments, reporting them to your doctor when possible.