What role do the kidneys play in diabetes type 2?
In Type 2 diabetes, the kidneys raise their production of glucose (a) by increasing gluconeogenesis and (b) by enhancing glucose reabsorption.
The kidneys play an important role in glucose homeostasis both by synthesizing glucose and by reabsorbing almost all the glucose that is filtered.
After a meal, the liver and muscles convert to glycogen about 75 % of the glucose ingested.
Overnight, glycogenolysis and gluconeogenesis return about 80 % of this glucose to the circulation.
The glomerulus filters about 180 g of glucose per day.
The proximal convoluted tubule (PCT) reabsorbs 99% of the glucose
Less than 500 mg/day are excreted in the urine.
The kidneys take up and metabolize about 10% of all glucose that the body uses.
They also have the enzymes to produce glucose by gluconeogenesis.
They account for about 40 % of total gluconeogenesis and 20% of all glucose released into the circulation.
In Type 2 diabetes (T2D}, renal glucose release increases by 300%, resulting in hyperglycemia.
Glucose transporters control the transport of glucose across the PCT membrane.
The activity of the glucose transporters increases in diabetes.
This allows more glucose to re-enter the circulation.
Hence, the kidneys contribute to hyperglycemia in T2D by (a) increasing gluconeogenesis and (b) by enhanced glucose reabsorption.