If it's because of Diabetes? (because there could be hundreds of causes)

But if it's because of Diabetes, high blood sugar over a number of years destroys the little blood capillaries that feed the skin, and the skin gets itchy due to lack of blood circulation

But you may just have dry skin due to weather or anything else so as suggested above, see your Doctor - can't treat when you don't know what the problem is

had to look up mostly dry skin and for old adult as they age see your doctor