My husband is 47 years old, 6'2", and weighs 285 lbs. His diet consists of junk food and beer. He is active and exercises moderately, alternating between lifting weights and walking on the treadmill. His toenail on his little toe turned black about two months ago, and even though it has been trimmed, it remains black. He has now developed a block spot on the toenail of his big toe on the opposite foot. Could these be signs of the onset of diabetes? He is VERY reluctant to go to the doctor.