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PubMed1988

Influence of timing in the fructosamine assay.

The fructosamine assay, based on the measurement of the reducing activity in serum at alkaline pH, provides an index of protein glycation. The reducing activity is expressed in equivalents of 1-deoxy-1-morpholinofructose (DMF) by direct comparison with the activity either of this synthetic compound or with a secondary protein standard calibrated against DMF. This study reports the influence of assay timing on the apparent serum fructosamine concentration. The kinetics of alkaline reducing activity in serum differed from that in both DMF and a secondary protein standard. When compared with DMF, activity in serum increased but decreased relative to the protein standard as the pre-incubation interval of the assay was shortened. The use of secondary protein standards results in underestimation of serum fructosamine concentrations when the pre-incubation phase of the assay is shorter than that used for the calibration of the secondary standard. Ascorbate exerted an inhibitory effect in fructosamine assays with pre-incubation times exceeding 5 min. The inhibition increased with both the concentration of ascorbate and the duration of the pre-incubation.

Ascorbic Acid↗
PubMed1988

Evaluation of a single-color-reading method for determining fructosamine.

A commercial kit for determining fructosamine was evaluated. The reference interval (determined from data on 183 nondiabetic subjects) was 1.67 to 2.85 (mean 2.17) mmol/L. Serum and plasma (EDTA- or heparin-anticoagulated) gave equivalent results; plasma treated with fluoride/oxalate gave slightly lower values. The between-run CV was less than 4%. Fructosamine values were similar by the present method and the kinetic method. The standard curve was linear in the range of 1.3 to 8.5 mmol/L. None of several constituents of blood that we tested appreciably interfered. Fructosamine values were increased in some lipemic samples from non-diabetics, and were significantly correlated with glycated hemoglobin as measured by affinity chromatography. This kit evidently is a suitable alternative to the kinetic method for determining fructosamine.

Adult↗
PubMed1987

Serum fructosamine level as a marker of glycemic control in diabetic patients with and without a residual C-peptide secretion.

Serum fructosamine was determined in 115 diabetic patients with a C-Peptide secretion (0.84 +/- 0.06 pmol/ml, mean +/- SEM) (Group A) and in 30 type I C-peptide negative totally insulin-dependent subjects (less than 0.05 pmol/ml) (Group B). A significant correlation between fructosamine and HbA1 values (r = 0.70, p less than 0.001) was evidenced in Group A. In contrast, such a correlation was not found in Group B (r = 0.33, p greater than 0.05). Fructosamine levels were also in good agreement with the physician's ratings of the degree of glycemic control in Group A, but not in Group B. It is concluded that the fructosamine measurement represents a complement rather than an alternative to HbA1, in particular in unstable diabetic patients.

Blood Glucose↗
PubMed1987

Plasma protein glycation as measured by fructosamine assay.

The fructosamine test for assessing control of glucose in blood has been extensively evaluated, but some questions remain regarding its validity. From the analytical and clinical evaluation we present here, we conclude that: the test is sensitive to variations in the composition of the sample protein; the fructosamine reaction is almost completely unaffected by labile fractions; the concentrations of fructosamine correlate well with the degree of glycation of total serum proteins, especially with glycated albumins and glycated immunoglobulins, as determined by affinity chromatography; the correlation with glycated hemoglobin (Hb A1c), measured as the stable fraction, is very poor, in diabetics treated with insulin (r = 0.373), or with oral hypoglycemic agents (r = 0.390); and (e) fructosamine and Hb A1c are, in fact, expressions of different periods of metabolic control and therefore have different clinical meanings.

Adolescent↗
PubMed1987

The usefulness of fructosamine determination in diabetic patients and its relation to metabolic control.

In 116 diabetics and 101 control subjects, we measured both HbA1 and fructosamine values, neither could definitely separate the 2 populations. We observed an excellent correlation between both variables and between each of them and various other parameters of metabolic control. It appeared that the correlation with recent (4 weeks) diabetes control was better with fructosamine than with HbA1 levels. The opposite was true when a 8 week period was considered. The presence of diabetic complications did not modify the fructosamine levels. These results confirm the value of fructosamine measurement in the evaluation of recent diabetes control, but clearly, HbA1 determination remains the best parameter of long-term glycemic control.

Blood Glucose↗
PubMed1986

[Assay for serum fructosamine in diabetes].

The serum fructosamine and some metabolic parameters such as glucose, glycosylated hemoglobin, cholesterol and triglycerides were evaluated in 190 diabetics and 80 controls. A good correlation of fructosamine values with glucose and glycosylated hemoglobin was found. These results and the high precision of fructosamine test confirm the importance of fructosamine determination for the evaluation of glycometabolic control in diabetics.

Adult↗
PubMed1987

Assay of serum fructosamine that minimizes standardization and matrix problems: use to assess components of biological variation.

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.

Adult↗
PubMed1985

Serum fructosamine in patients with diabetes mellitus.

Serum fructosamine was compared with other measures of blood glucose control in 11 non-diabetic volunteers, 14 type 1 and 14 type 2 diabetic patients. Estimates of mean plasma glucose concentrations for the 28 diabetic patients were made by nine physicians, based on their interpretation of historical data, home capillary blood glucose profiles, fasting and random plasma glucose and plasma lipid levels. Significant differences between estimated and measured mean glucose levels were apparent with a tendency for physicians to underestimate mean blood glucose in the hyperglycaemic range (glucose greater than 11 mmol/l). Fructosamine results on the same patients correlated linearly both with mean plasma glucose concentrations (r = 0.86, p less than 0.001) and with glycosylated haemoglobin (HbA1c) levels (r = 0.93, p less than 0.001) and correctly classified diabetes control in most patients. Despite marked fluctuations of plasma glucose concentration, serum fructosamine levels measured at different times of the day did not alter significantly. We conclude that a random serum sample analysed for fructosamine provides a simple and reliable means to measure the efficacy of therapy and often provides information superior to clinical assessment of diabetic control.

Adolescent↗
PubMed1985

Measurement of plasma fructosamine evaluated for monitoring diabetes.

The mean fructosamine concentration in plasma of diabetics (n = 200) differed significantly (p less than 0.001) from those of a hospitalized nondiabetic population (n = 163)--the latter mean being essentially the same for ambulatory subjects (n = 145), expectant mothers (n = 58), and patients with renal failure (n = 31), regardless of sex. In the diabetic group, values for plasma fructosamine correlated with those for glycated hemoglobin (r = 0.767, p less than 0.01) and glycated protein (r = 0.817, p less than 0.01). Values for plasma fructosamine were stable from day to day in patients with controlled blood glucose, but fluctuated in certain patients receiving only parenteral nutrition, even when their concentrations of glucose were normal and stable. We conclude that measurement of plasma fructosamine is suitable for assessing intermediate-term control of blood glucose when the turnover of plasma proteins is normal.

Blood Glucose↗
PubMed1985

Use of protein-based standards in automated colorimetric determinations of fructosamine in serum.

We have developed an automated colorimetric assay for glycated serum proteins (or fructosamines), measuring the reducing activity of serum in alkaline solution (pH 10.35) at 37 degrees C. The calibrants were prepared from a synthetic fructosamine (1-deoxy-1-morpholinofructose), although secondary standards of glycated bovine albumin were more robust in routine application. Interference was appreciable only with icteric specimens (bilirubin greater than 60 mumol/L), and between-batch imprecision (CV) was less than 2%. The range of fructosamine concentrations measured in 502 healthy (nondiabetic) blood donors was 1.87-2.87 mmol/L. There were no significant (p greater than 0.05) age- or sex-related differences in this population sample. Fructosamine accurately reflected blood glucose control as evidenced by the significant correlation with glucose concentrations in fasting plasma (r = 0.82, p less than 0.001) and with glycated hemoglobin (HbA1c) (r = 0.87, p less than 0.01) in 115 patients with type 2 (non-insulin-dependent) diabetes mellitus. The test is simple and rapid to perform (75 samples per hour) and provides an alternative to HbA1c determinations for monitoring blood glucose control and assessing the effects of changes in diabetes management.

Adolescent↗
PubMedDate not supplied

[Determination of fructosamine in the early diagnosis of disorders of carbohydrate metabolism].

Blood serum fructosamine level were measured on an empty stomach in 97 normal subjects and subjects with various disorders of carbohydrate metabolism (the so-called "pre-diabetes" and changed glucose tolerance) in order to elucidate the significance of this factor as a marker of such disorders. Fructosamine concentrations were for the first time measured in children whose parents suffered from insulin-dependent or noninsulin-dependent diabetes mellitus. The content of fructosamine on an empty stomach was found to depend on the degree of carbohydrate metabolism disorders, increasing with the progress of these disorders. The findings permit a conclusion on the possibility of using fructosamine as a marker for the diagnosis of "pre-diabetes" in subjects with its levels of 2.5 to 2.99 mmol/l and of disordered glucose tolerance in those with its levels over 3 mmol/l and glucose level on an empty stomach no more than 6 mmol/l.

Adolescent↗
PubMedDate not supplied

[Comparison of fructosamine, glycosylated hemoglobin and glucose in patients with type II diabetes].

The levels of blood glucose, glycosylated hemoglobin, and fructosamine were measured in 57 patients with type II diabetes in order to elucidate the value of measurements of glycosylated proteins in assessment of the disorders of carbohydrate metabolism. A highly significant correlation between the levels of glucose and fructosamine was revealed (r = 0.81, p < 0.05) and a reliable, though less significant one, between the levels of glucose and glycosylated hemoglobin (r = 0.55, p < 0.05) and those of fructosamine and glycosylated hemoglobin (r = 0.63, p < 0.05). Similarity between correlation coefficients for fructosamine and glucosylated hemoglobin with the mean concentration of glucose during both the first and second preceding months permits an assumption that the degree of metabolic control of carbohydrate metabolism in the examined patients was stable for at least 2 months.

Autoanalysis↗
PubMed1994

[A method of estimation for prevalence of diabetes mellitus from fructosamine levels].

A method for estimating the prevalence interval of diabetes mellitus from fructosamine data is presented, which is based on the previously reported method for estimating prevalence from results of screening tests and on the results of 75 gram glucose tolerance test and fructosamine test in 1,359 examinees. Where true prevalences are 1-20% and population size is 100-10,000, the estimates for prevalence of diabetes mellitus are generally minimum when a screening level of 310 mumol/l of fructosamine is utilized. In our method, a screening level for fructosamine of 310 mumol/l was specified. Standard error ratios of estimated prevalence of diabetes mellitus to true prevalence in a population with an actual prevalence of 10% were about 40% for a population of 200 persons, and about 20% for 2,000 persons or more.

Diabetes Mellitus↗
PubMedDate not supplied

[Correlation of glycosylated hemoglobin and fructosamine in pregnant women with diabetes mellitus].

Glycolisated hemoglobin (HBA1c), fructosamine, glucose, albumin and total proteins were estimated 40 healthy pregnant women and 90 pregnant women with diabetes mellitus. Fructosamine was estimated by NBT method with "Fructosamine test" commercially available kit on Technicom automatic analyser RA-1000. Glucose was determined on Beckmman glucose analyser. HBA1c was assayed by Bio-Rad test, while albumin and total proteins by Beckmman tests. We found best correlation between fructosamine and HBA1c at pregnant women who were on dietary therapy worst at pregnancy women on insulin therapy.

Female↗
PubMed1993

Mechanism of fructosamine assay: evidence against role of superoxide as intermediate in nitroblue tetrazolium reduction.

We studied the chemistry of the fructosamine assay for glycated serum proteins by using the model Amadori compound N alpha-formyl-N epsilon-fructoselysine (fFL), an analog of glycated lysine residues in protein. Free lysine was formed at approximately 70% yield during a standard 20-min incubation of fFL with alkaline nitroblue tetrazolium (NBT) at 37 degrees C. Although superoxide dismutase (SOD; EC 1.15.1.1) and catalase (EC 1.11.1.6) decreased the yield of the product, monoformazan dye (MF+), the yield of MF+ was slightly greater under anaerobic than aerobic conditions, excluding a role for superoxide as an intermediate in the reduction of NBT during the fructosamine assay. SOD added to diabetic patients' sera at physiological concentrations also caused a significant (approximately 50%) inhibition of MF+ formation. This inhibition was reduced by addition of nonionic detergents, which contain organic peroxide inhibitors of SOD, to the fructosamine reagent. Overall, these data indicate that the Amadori compound is the direct reductant of NBT in the fructosamine assay and that superoxide is not an intermediate in the reaction. The inhibitory effects of SOD and catalase are most likely the result of oxygen regeneration in the assay mixture.

Catalase↗
PubMed1993

[The fructosamine monitoring of the effect on glycemic control of hypocaloric parenteral nutritional support with glycerol].

The objective of this paper is to examine the usefulness of plasmatic fructosamine finding as an indicator of glycemic control in patients with hypocaloric parenteral nutrition with glycerol. Thirty abdominal surgery patients were studied. None displayed malnutrition, diabetes mellitus, hepatopathy, nephropathy or hyperlipemia in the preoperative stage or during the five days of postoperative recovery they were administered hypocaloric parenteral nutrition with glycerol. Their plasma levels of glucose, fructosamine, triglycerides, albumin and total proteins were found in the preoperative stage and on the first and fourth day of postoperative recovery. Following surgery, findings showed an increase in triglycerides and a decrease in the protein compartment, while glycemia levels remained steady. Furthermore there was a positive correlation between the figures for glycemia and later fructosamine figures. The conclusion was that providing hypocaloric nutrition with glycerol does not increase fructosamine levels. This confirmed prior observations on the slightness of its effect on hydrocarbonic metabolisms.

Abdomen↗
PubMed1996

Technical performance evaluation of BM/Hitachi 747-200 serum fructosamine assay.

The technical performance of serum fructosamine assay as a short-term index of diabetic control was evaluated by using the BM/Hitachi 747-200 Automatic Analyzer (Boehringer Mannheim Corp). Intra- and interassay precisions (CV) were <2%. Linearity was confirmed up to 1000 micromol/L. Lipemia, produced artificially or from hypertriglyceridemia in vivo, did not interfere with measurement of serum fructosamine concentration. However, hemoglobin (Hb) interfered with measurement substantially at concentrations >15.5 micromol/L, and bilirubin interfered substantially at concentrations >68.4 micromol/L. A normal reference range of up to 282 micromol/L (mean +/- 2SD = 242 +/- 40) was derived from results obtained from 228 nondiabetic subjects. In 222 diabetic subjects, serum fructosamine concentration correlated well with fasting glucose concentration (r = 0.74) and with Hb A1c concentration (r = 0.80). This automated fructosamine assay has the advantages of technical simplicity, low cost, and reduced analytical time compared with the Hb A1c method.

Autoanalysis↗
PubMed2006

A convenient HPLC assay for the determination of fructosamine-3-kinase activity in erythrocytes.

Fructosamine-3-kinase (FN3K) mediates the regeneration of lysine from fructosamines formed on proteins as a result of the 'early' Maillard reaction. As fructosamines and advanced glycation endproducts derived therefrom are supposed to play an adverse role in the development of diabetic complications, FN3K is discussed as a protein-repairing enzyme. In this study, a method for the determination of FN3K activity in erythrocyte lysate is described which overcomes the complexity of currently known assays. The assay is based on the FN3K-dependent conversion of the synthetic UV-active fructosamine Nalpha-hippuryl-Nepsilon-(1-deoxy-D-fructosyl)lysine (BzGFruK) to Nalpha-hippuryl-Nepsilon-(phosphofructosyl)lysine (BzGpFruK). The FN3K activity was quantified by measuring the formation of BzGpFruK using RP-HPLC with UV detection. Identification of the metabolite BzGpFruK was achieved by means of UV and mass spectroscopy. The results are related to the content of haemoglobin for standardisation. First activity measurements with a chosen number of normoglycaemic subjects confirmed the convenient applicability of the method and showed distinctly different individual activities, as already discovered recently. The new established assay needs only the equipment of a routine laboratory with HPLC instrumentation. This should facilitate further studies about a possible relationship between the FN3K activity and the development of diabetic complications.

Adult↗