Pathologic changes in
the small blood vessels and capillaries of the eye and kidney are
responsible for the development of diabetic retinopathy and the Kimmelstiel-Wilson
syndrome in patients with diabetes mellitus.
important pathologic change is the prominent accumulation of basement
membrane-like material around the vessels.
microscopy studies have shown that this basement membrane change is not
limited to only the eye and kidney but occurs also in capillaries of the
muscle and skin of diabetic patients.
nondiabetic persons, thickening of muscle capillary basement membranes
occurs in a linear fashion in males with increasing age, where as in females
the basement membrane thickness increases until about 40 to 50 years of age,
reaches a plateau, and increases again between 60 and 70 years of age.
evidence indicates that diabetic microangiopathy is a complication of the
diabetic state and is not attributable to a separate genetic defect.
It would appear that the
changes are caused by the inability of maintaining the blood glucose within
normal limits at all times with insulin therapy.
These findings are of great
importance, since they provide hope that if the diabetic state could be
reverted to normal by new therapeutic means the
early stage of the complications could be reverted and further progression
of these lesions could be halted.
Kidney in diabetes:
Nodular lesions of the glomeruli and
thickening of basement membrane
nodular lesions of the glomeruli described by Kimmelstiel and Wilson are
characteristic pathologic changes found in the kidney in diabetes mellitus.
This lesion is
the result of focal thickening of the basement membrane.
Electron microscopic studies
of the glomeruli in diabetic patients have demonstrated that the earliest change occurs in the mesangial area of the glomerulus.
is a thickening of the basement membrane in this area and an increase in the
number of mesangial cells.
Serial renal biopsies on
these diabetic patients over a period of years have shown that the amount of
basement membrane in the kidney gradually
increases and results in the formation of the nodular lesions.
These findings clearly
indicate that the basement membrane changes result from the diabetic
Vacuolization of the cells
of proximal convoluted tubules at the corticomedullary junction may be
observed in patients dying of uncontrolled diabetes and severe
These sub-nuclear vacuoles have been reported to represent
areas of glycogen deposition within the tubules.
These vacuoles disappear
when the hyperglycemia is maintained within normal limits. This condition is
called the 'Armanni Ebstein lesion of the kidney'.
More recent studies show
them to contain fat.
Necrotizing renal papillitis
is a rare but serious complication of diabetes mellitus.
This condition is
not limited to diabetic patients but can also occur in non-diabetic persons
with obstructive lesions of the urinary tract.
The condition is
characterized clinically in the diabetic patient by the rapid onset of
uremia and subsequent death caused by infarction and sloughing of the renal