Final answer:
The first manifestation of diabetic nephropathy is microalbuminuria, which indicates early kidney damage from diabetes through the presence of albumin in the urine.
Step-by-step explanation:
Diabetic nephropathy is a progressive kidney disease caused by damage to the capillaries in the glomeruli of the kidneys. This condition particularly affects individuals with a long history of diabetes mellitus, and risks are amplified by poor glucose control, high blood pressure, smoking, and family history of kidney issues. When considering the manifestations of diabetic nephropathy, microalbuminuria is often the initial clinical sign detected, indicating the presence of albumin in the urine.
This preliminarily occurs due to the inability of the damaged glomerular capillaries to prevent albumin from leaking into the urine. Management strategies for this condition include the use of medication to lower protein levels in the urine, strict blood sugar control, and hypertension management. While other symptoms such as decreased serum urea nitrogen levels and the development of Kimmelstiel-Wilson nodules may occur, they are not the initial manifestations of diabetic nephropathy.