Renal substrate exchange in human diabetes mellitus

Area of Science:

• Nephrology
• Endocrinology
• Metabolic Research

Background:

• Insulin-dependent diabetes mellitus (IDDM) is characterized by hyperglycemia.
• The kidney's role in glucose metabolism, particularly gluconeogenesis, in diabetic patients requires clarification.

Purpose of the Study:

• To investigate renal substrate exchange in patients with IDDM.
• To determine if the kidney produces glucose in non-ketoacidotic diabetic individuals.

Main Methods:

• Renal vein catheterization was performed in five male patients with IDDM.
• Para-aminohippuric acid (PHA) clearance was used to measure effective renal blood flow.
• Renal substrate uptake and release (glucose, glycerol, pyruvate, amino acids) were quantified.

Main Results:

• Despite moderate fasting hyperglycemia (16.8 +/- 1.5 mmol/L), no net glucose release from the kidney was observed.
• A significant net renal uptake of glucose (320 +/- 80 mumol/min) was detected.
• The kidney showed net uptake of glycerol and net release of pyruvate; renal amino acid exchange patterns were similar to healthy subjects.

Conclusions:

• The kidney does not contribute to net glucose production in non-ketoacidotic diabetic patients.
• Renal amino acid exchange in diabetics mirrors that of healthy individuals.
• The human kidney is not a major gluconeogenic organ in the context of diabetes.