I am uncertain why your doctors thought that the skin changes you are experiencing were related to diabetes or another serious medical problem, however I think this underscores how you should not feel that you need to suffer from medical problems without seeking help. I strongly suggest going to see your primary care doctor
and talking about your symptoms.
Itching, scaling skin that occurs primarily in the creases of the face and that resulting in flaking off of the scale sounds a lot like seborrheic dermatitis to me. This is a type of skin inflammation that is quite common, and may in part be related to fungus growing on the skin. Other common areas affected include the scalp, hairline, and eyebrows. Often good skin hygiene can help, as can an over the counter steroid cream. If these do not work, then your doctor can suggest stronger medications.
There are several other possibilities for this skin problem other than seborrheic dermatitis, including psoriasis
and eczema. In order to confirm a diagnosis and decide on an appropriate treatment, the important first step is for you to set up an office visit with your primary care doctor! The good news is that there is almost certainly a good treatment option for you!