Diabetes is a very serious disease with not controlling it leading to damage of the eyes, nervous system, heart, kidney and liver. Diabetes damages the blood vessels in the eyes leading to glaucoma, cataracts, structural changes to your retina, even blindness. This hampers nerve signals to the eye and compress eye nerves and other structures.
This lifestyle disease could damage the nerves circulating glucose rich blood and lead to numbness, and tingling and pain, especially in the legs and feet. Cuts and sores may take time to heal with numbness leading to severe consequences as amputation. Diabetes increases your risk of heart disease and stoke by 100% over non-diabetics as the blood vessels get both damaged and narrow.
The kidney could also find it harder to filter the high content of sugar in the blood and this could lead chronic kidney disease ending up in its failure. Diabetes can damage the liver and make it difficult for this organ to process fats, with scarring of the liver leading to cirrhosis of the liver.