1-deoxy-1-morpholinofructose and Diabetes-Mellitus

To determine glycoserum, the nitroblue tetrazolium (NBT) assay is quick, economical, convenient and easily automated. This method, however, is vulnerable to interference by thiol group, which should not be ignored during the analysis.. Thiol group in glycoserum was blocked with iodoacetamide (IAM) before NBT was added. The reaction was carried out in a thermal bath and terminated on ice. The absorbance was measured at either 570 or 530 nm.. IAM (3-10 mmol/l) did not give any detectable interference in the NBT assay. The absorbance at both 570 and 530 nm was linearly related to the concentration of either glycoserum or 1-deoxy-1-morpholino-D-fructose (DMF) that had been treated with IAM. The assay showed a good discrimination between diabetic and normal subjects (t-test, P < 0.001). Uric acid and lipemia under physiological conditions did not interfere with NBT reaction. The assay was affected by hyperlipemia and hematolysis.. IAM-modified method prevented NBT assay from the interference by thiol group and uric acid.

Topics: Blood Glucose; Diabetes Mellitus; Fructose; Glycated Hemoglobin; Humans; Hyperlipidemias; Iodoacetamide; Morpholines; Nitroblue Tetrazolium; Spectrum Analysis; Sulfhydryl Compounds; Uric Acid

Methodological problems with the assay of fructosamine in serum--standardization, matrix effects, and dependence on buffer pH--have been minimized with a method involving colorimetric assay of each specimen and subsequent re-assay after standard addition of 1-deoxy-1-morpholinofructose. Absorbance at optimum wavelength of 540 nm varies linearly with fructosamine concentration to at least 5.5 mmol/L, and between-run precision is about 6% for both patients' specimens and quality control materials. Correction of fructosamine to serum albumin of 40 g/L minimizes the effect of albumin while maintaining transferability of data and reference values. From data on biological variation, the analytical goal for precision (CV) is less than or equal to 2.6%. The square root of the ratio of intra- to interindividual variance is low, indicating that fructosamine concentrations have a high index of individuality; thus conventional population-based reference values are of limited use. Although this assay may be useful in monitoring disease, we doubt that it provides a valid screening test for diabetes.

Topics: Adult; Colorimetry; Diabetes Mellitus; Female; Fructosamine; Fructose; Hexosamines; Humans; Hydrogen-Ion Concentration; Kinetics; Male; Middle Aged; Morpholines; Quality Control; Serum Albumin; Spectrophotometry; Statistics as Topic

Topics: Blood; Blood Proteins; Diabetes Mellitus; Fructosamine; Fructose; Glycated Serum Proteins; Glycoproteins; Hexosamines; Humans; Morpholines; Quality Control; Spectrophotometry

A method is presented for the estimation of fructosamine using a Cobas Bio centrifugal analyser. The effect of three different preparations of human serum albumin used for construction of calibration curves of 1-deoxy-1-morpholinofructose is described. The selection of serum albumin and the concentration used in the standard solutions is critical since the dose-response curve is affected differently and will therefore influence the estimated values. Normal ranges were obtained for non-diabetic subjects with normal protein status and for a group of females with reduced albumin levels due to pregnancy or oestrogen therapy. There was no significant difference between fructosamine levels in these populations. Fructosamine was also estimated in 250 patients attending a diabetic out-patient department and this correlated well with haemoglobin A1 estimated simultaneously. The method is rapid, technically simple and inexpensive and may prove to be a useful and reliable alternative to HbA1 estimation.

Topics: Adolescent; Adult; Aged; Diabetes Mellitus; Female; Fructosamine; Fructose; Glycated Hemoglobin; Hexosamines; Humans; Male; Middle Aged; Morpholines; Nitroblue Tetrazolium; Oxidation-Reduction; Pregnancy; Reagent Kits, Diagnostic; Reference Values; Serum Albumin