Transcapillary colloid osmotic gradient, plasma volume and interstitial fluid volume in long-term type 1 (insulin-dependent) diabetes.

Plasma and subcutaneous colloid osmotic pressure, transcapillary escape rate of albumin, plasma volume and extracellular fluid volume were measured in 10 long-term Type 1 (insulin-dependent) diabetic patients without clinical nephropathy. Interstitial colloid osmotic pressure was reduced compared with normal subjects (12.9 +/- 3.0 versus 15.8 +/- 2.7 mmHg, p less than 0.05) and the transcapillary colloid osmotic gradient increased (17.0 +/- 2.4 versus 12.8 +/- 2.7 mmHg, p less than 0.01). Plasma volume was in the normal range and interstitial fluid volume increased by approximately 21% compared with normal subjects (p less than 0.01). Transcapillary escape rate of albumin was significantly increased compared with normal subjects (8.9 +/- 1.9 versus 5.1 +/- 1.6% h, p less than 0.01). A negative correlation was found between the transcapillary colloid osmotic gradient and interstitial fluid volume (r = 0.6, 0.01 less than p less than 0.05). These results suggest that the increased small vessel permeability in long-term diabetes leads to wash-out of interstitial proteins and the resulting increased transcapillary colloid osmotic gradient tends to preserve the plasma volume and to limit the tendency to increased interstitial fluid volume.