How does poorly controlled diabetes lead to kidney failure?
The major cause of kidney failure due to complications from diabetes is because of diabetic nephropathy, or damage of the nephrons which make up the kidneys because of excess blood-sugar. When the kidneys are unable to process blood and filter out impurities, blood waste builds up in the body and the damage continues. The exact correlation is still unknown; one possibility is that excess blood-sugar overstimulates the kidneys, causing them to increase their function when there is not a lot of fluid to filter. This overreaction can cause the nephrons to thicken and/or shut down, speeding damage to the kidneys. By controlling blood-sugar, kidney damage can be decreased and even eliminated for a long time; many diabetics lose their kidney function eventually and require transplantation or dialysis.
The main function of kidney is filteration of toxic substance from the body, they remove waste and toxins from the blood and this function has to take place 24 hours. They also produce key hormone essential for the production of RBC. Kidney also play role in maintaining the blood preasure.
In a diabetes patient with increase in blood glucose it damages the small blood vessels that can lead to the damage of the kidney which may also lead to the kidney failure, due to which there is also increase in the blood preasure.