A study of the effect of diet on glycosylated haemoglobin and albumin levels and glucose tolerance in normal subjects.

As factors other than the degree of glucose tolerance or ambient blood glucose may determine glycosylated haemoglobin levels, we have investigated the effects of dietary glucose and soluble fibre supplementation on glucose tolerance, glycosylated haemoglobin and glycosylated albumin in non-diabetic subjects. Eleven non-diabetic subjects (7 M, 4 F; age 26.5 +/- 6.5 (+/- SD) yr; BMI 21.6 +/- 3.1 kg m-2) followed a high-soluble-fibre (5 g guar gum thrice daily)/low-glucose diet, or a low-soluble-fibre/high-glucose (500 ml glucose drink providing 100 g glucose per day) diet, each for 6 weeks, in randomized order. A 75 g oral glucose tolerance test was performed at recruitment and after each diet period, and fasting blood was assayed for glycosylated albumin by affinity chromatography, and glycosylated haemoglobin by four different methods. Adherence to guar and glucose supplementation was assessed at 89.5 +/- 7.5% and 97.1 +/- 3.5%, respectively. There was no significant effect of either diet on mean fasting, 1-h or 2-h plasma glucose concentration, or glycosylated haemoglobin levels by any assay. Glycosylated albumin was 1.71 +/- 0.35% at entry, fell to 1.33 +/- 0.30% (p less than 0.01) with high-fibre and rose to 1.95 +/- 0.23% (p less than 0.02) after a high-glucose diet. Insulin, total- and HDL-cholesterol and triglyceride levels were unaffected by either diet. A high-glucose diet increases, and a high-soluble-fibre diet decreases, levels of glycosylated albumin without effects on glucose tolerance or glycosylated haemoglobin.