Evaluation of the fructosamine test for the measurement of plasma protein glycation

1-Amino-1-deoxy-d-fructose ("fructosamine") and its derivatives

Fructosamine has long been considered as a key intermediate of the Maillard reaction, which to a large extent is responsible for specific aroma, taste, and color formation in thermally processed or dehydrated foods. Since the 1980s, however, as a product of the Amadori rearrangement reaction between glucose and biologically significant amines such as proteins, fructosamine has experienced a boom in biomedical research, mainly due to its relevance to pathologies in diabetes and aging. In this chapter, we assess the scope of the knowledge on and applications of fructosamine-related molecules in chemistry, food, and health sciences, as reflected mostly in publications within the past decade. Methods of fructosamine synthesis and analysis, its chemical, and biological properties, and degradation reactions, together with fructosamine-modifying and -recognizing proteins are surveyed.

Developing targeted drug delivery carriers for breast cancer using glutathione-sensitive doxorubicin-coupled glycated bovine serum albumin nanoparticles

Incorporation of the nano-based carriers into drug delivery provides a promising alternative to overcome the limitations of the conventional chemotherapy. Doxorubicin (DOXO) is an effective chemotherapeutic drug widely used in chemotherapy for breast cancer treatment. A globular protein bovine serum albumin (BSA) holds great potential as carriers in pharmaceutical applications. This work is aimed at developing the DOXO-coupled glycated BSA nanoparticles via desolvation method for improving the capability of targeting the GLUT5 transporters over-expressed on breast cancer cells. Fructosamine assay and Fourier transform infrared spectroscopy were employed to determine the content of fructosamine structure and structural changes on the surfaces of nanoparticles, respectively. Additionally, the synthesized BSA nanoparticles were further characterized by electron microscopy and dynamic light scattering. Results revealed that the DOXO-coupled glycated BSA nanoparticles were spherically shaped with a hydrodynamic diameter of ~60.74 nm and a ζ-potential of ~ - 42.20 mV. Moreover, the DOXO release behavior of as-synthesized DOXO-coupled glycated BSA nanoparticles was examined under different conditions. Finally, the DOXO-coupled glycated BSA nanoparticles were found to exhibit cytotoxicity toward both MCF-7 and MDA-MB-231 cells. Our findings evidently suggested that the drug-coupled glycated BSA nanoparticles serve as the potential candidates for targeted drug delivery platform used in breast cancer therapy.

Telemonitoring in fasting individuals with Type 2 Diabetes Mellitus during Ramadan: A prospective, randomised controlled study

We determined the impact of a remote blood glucose telemonitoring program with feedback in type 2 diabetes mellitus patients fasting during Ramadan compared to conventional self-monitoring method. A twelve-week cluster randomised study, with 85 participants who wish to fast for at least 15 days during Ramadan was conducted. Self-measurement and transmission of blood glucose results were performed six times daily during Ramadan. Results were transmitted to a secure website for review with feedback from case manager if necessary. The control group received usual care. The main outcome was the number of participants experiencing hypoglycaemia during Ramadan and at the end of the study. During Ramadan, the number of participants reporting hypoglycaemia was significantly lower in the telemonitoring group [Odds ratio (OR): 0.186, 95% confidence interval: 0.04-0.936; p = 0.04]. Similarly, the proportion of participants reporting symptomatic hypoglycaemia at the end of the study was significantly lower in the telemonitoring group (OR: 0.257, 95% CI: 0.07-0.89; p = 0.03). A reduction of 1.07% in glycated haemoglobin levels was observed in the telemonitoring group compared to 0.24% in the control group (p < 0.01). Overall, telemonitoring was a useful adjunct to reduce the risk of hypoglycaemia during Ramadan with no deterioration in glycaemic control.

Ascorbic acid supplementation improves skeletal muscle oxidative stress and insulin sensitivity in people with type 2 diabetes: Findings of a randomized controlled study

AIM/HYPOTHESIS

Skeletal muscle insulin resistance and oxidative stress are characteristic metabolic disturbances in people with type 2 diabetes. Studies in insulin resistant rodents show an improvement in skeletal muscle insulin sensitivity and oxidative stress following antioxidant supplementation. We therefore investigated the potential ameliorative effects of antioxidant ascorbic acid (AA) supplementation on skeletal muscle insulin sensitivity and oxidative stress in people with type 2 diabetes.

METHODS

Participants with stable glucose control commenced a randomized cross-over study involving four months of AA (2 × 500 mg/day) or placebo supplementation. Insulin sensitivity was assessed using a hyperinsulinaemic, euglycaemic clamp coupled with infusion of 6,6-D2 glucose. Muscle biopsies were measured for AA concentration and oxidative stress markers that included basal measures (2',7'-dichlorofluorescin [DCFH] oxidation, ratio of reduced-to-oxidized glutathione [GSH/GSSG] and F2-Isoprostanes) and insulin-stimulated measures (DCFH oxidation). Antioxidant concentrations, citrate synthase activity and protein abundances of sodium-dependent vitamin C transporter 2 (SVCT2), total Akt and phosphorylated Akt (ser473) were also measured in muscle samples.

RESULTS

AA supplementation significantly increased insulin-mediated glucose disposal (delta rate of glucose disappearance; ∆Rd) (p=0.009), peripheral insulin-sensitivity index (p=0.046), skeletal muscle AA concentration (p=0.017) and muscle SVCT2 protein expression (p=0.008); but significantly decreased skeletal muscle DCFH oxidation during hyperinsulinaemia (p=0.007) when compared with placebo. Total superoxide dismutase activity was also lower following AA supplementation when compared with placebo (p=0.006). Basal oxidative stress markers, citrate synthase activity, endogenous glucose production, HbA1C and muscle Akt expression were not significantly altered by AA supplementation.

CONCLUSIONS/INTERPRETATION

In summary, oral AA supplementation ameliorates skeletal muscle oxidative stress during hyperinsulinaemia and improves insulin-mediated glucose disposal in people with type 2 diabetes. Findings implicate AA supplementation as a potentially inexpensive, convenient, and effective adjunct therapy in the treatment of insulin resistance in people with type 2 diabetes.

The impact of intra-articular methylprednisolone acetate injection on fructosamine levels in diabetic patients with osteoarthritis of the knee, a case-control study

Fructosamine is a glycated protein that reflects blood glucose control over the last 2-3 weeks. There are no studies that address the impact of intra-articular injection (IAI) of methylprednisolone acetate (MPA) on fructosamine levels among patients with type-2 diabetes and osteoarthritis of the knee (OAK). Non-selected patients attending the rheumatology or orthopedic clinic with type-2 diabetes and painful OAK, who failed non-steroidal anti-inflammatory drugs (NSAIDS) and physical therapy, were asked to participate in our study. After consent blood tests were drown for fructosamine, hemoglobin A1c (HbA1c) level, complete blood count, lipid profile, serum albumin, serum protein, c-reactive protein, and erythrocyte sedimentation rate. Demographic and different clinical parameters were also documented. Immediately after that, patients had IAI of 80 mg of MPA at the knee joint (group 1). Two to three weeks later, the same blood tests were repeated (except for HbA1c). Age- and sex-matched group of patients with type-2 diabetes and painful OAK attending the same clinics, but who were managed by NSAIDS were asked to participate as a control group (group 2) and had the same evaluation at enrollment and 2-3 weeks later, after consent. Eighteen patients from either group completed the study. Mean fructosamine level in group 1 patients was 263.7 ± 31.8 mg% prior to the IAI vs. 274.6 ± 39.3 mg% (p = 0.035), 2-3 weeks later, while mean fructosamine level in the control group (group 2) at enrollments was 274.2 ± 31.2 mg% vs. 269 ± 30.2 mg%, p = 0.509, 2-3 weeks later. There was no significant change in any other parameter tested at enrollment in either group, compared to those obtained 2-3 weeks afterwards. Body mass index was on the edge of significance as a predictor for a significant change in fructosamine level in group 1 patients. IAI of 80 mg of MPA in patients with type-2 diabetes and OAK had resulted in a significant, though mild increase in fructosamine levels 2-3 weeks later.

Implication of corticotropic hormone axis in eating behaviour pattern in obese and type 2 diabetic participants

In Algeria, eating behaviour has been increasingly deviated from its traditional Mediterranean diet to modern fast food style. The present study examines the interactions between eating behaviour pattern (EBP), corticotropic hormone axis and the metabolic syndrome. Our Algerian population cohort comprised of 410 participants (130 obese, 170 type 2 diabetics and 110 healthy participants). The EBP was evaluated by the Three-Factor Eating Questionnaire test. The anthropometric and metabolic parameters (glucose, TAG, HDL, LDL and cholesterol) and the concentrations of hormones (insulin, adrenocorticotropin hormone (ACTH), cortisol and growth hormone) were determined by biometrics, spectrophotometry and RIA, respectively. Multivariate analyses showed a high correlation between the EBP and the metabolic syndrome, particularly between insulin-resistant state and hypertrophy of visceral adipose tissue. Compared with healthy participants, obese ones showed the hyperphagic type of EBP, i.e. disinhibition and hunger disorders. Conversely, the diabetics showed both the hypophagic and hyperphagic type of EBP. In diabetic and obese participants, cortisol and ACTH secretions were significantly altered, leading to metabolic disorders. The present study confirms the role of EBP in obesity and diabetes.

Elevated pregnancy losses at high and low extremes of maternal glucose in early normal and diabetic pregnancy: evidence for a protective adaptation in diabetes

OBJECTIVE

Early pregnancy losses increase with marked hyperglycemia in diabetic pregnancy. However, mean loss rates do not differ from those of nondiabetic pregnancy. This observation might be explained by increased fetal losses at the extremes of glycemia in diabetic and nondiabetic pregnancy. To test this hypothesis, we examined relationships of proximate measures of prior glycemia, glycated protein and fructosamine, to pregnancy loss.

RESEARCH DESIGN AND METHODS

A total of 389 diabetic and 429 nondiabetic pregnant subjects participated in the Diabetes In Early Pregnancy study. Glycated protein and fructosamine measurements were standardized as multiples of control values for each center (Z score). The logarithm of odds of pregnancy loss were plotted against Z scores and tested by logistic models.

RESULTS

Mean pregnancy loss rates were 12% in diabetic and 13% in normal pregnancies. However, over six intervals of glycated protein in diabetic pregnancy, fetal loss rates at the upper and lower extremes (24 and 33%, respectively) were approximately threefold higher than the four intervening rates (8-14%). The odds ratio of pregnancy loss for these extreme intervals to the intervening intervals is 3.0 (P = 0.01). Nondiabetic losses showed a similar pattern. In confirmation, logit pregnancy losses were increased in a J-shaped curve at the glycemic extremes in normal (P < 0.019) and diabetic (P < 0.015) pregnancy. The upper glycemic extreme in diabetic pregnancy was two- to fivefold higher than in control pregnancy.

CONCLUSIONS

Pregnancy losses are increased at the extremes of glycemia in both normal and diabetic pregnancy but at higher levels in diabetic pregnancy. The data suggest defensive adaptations against hyperglycemia in diabetic pregnancy.

Variability characteristics and test selection in herd-level nutritional and metabolic profile testing

Nutritional assessment based on animal response factors is the basis of essentially all dietary recommendations. Blood concentrations of nutrients, metabolites, and hormones are important animal response factors associated with nutriture, making blood analysis an important nutritional assessment technique. There are, however, numerous sources of variability, other than nutrition, affecting the concentration of blood analytes used in nutritional assessment. Minimizing the effects of non-nutrient sources of variability and maximizing the effects of nutritional variability is the objective in designing strategies for blood sampling and testing for nutritional assessment. Important non-nutrient sources of variability are age, sex, gestation stage, lactation stage and milk yield, and season. When interpreting test results, grouping animals by these characteristics is an important means of minimizing the effects of non-nutritional variability. Within these groups, it is important to take an adequate number of samples, generally starting out with at least seven. Finally, selecting appropriate tests is critical. Tests commonly used for clinicopathologic evaluations are not necessarily the best tests for nutritional assessment. Analytes should be chosen that are likely to have a large portion of their total variability caused by nutritional effects. This generally does not include those metabolites the blood concentrations of which are rigidly controlled by homeostatic forces.

Glycated hemoglobin of fractionated erythrocytes, glycated albumin, and plasma fructosamine during pregnancy

OBJECTIVE

To evaluate glucose metabolism during pregnancy, we measured plasma fructosamine, glycated albumin, and the stable glycated hemoglobin of the light and dense erythrocytes.

STUDY DESIGN

The abnormal glucose tolerance group comprised patients with gestational diabetes and those with one abnormal value on a 75 gm oral glucose tolerance test. Erythrocyte fractionation was performed by capillary centrifugation.

RESULTS

In normal pregnancy glycated hemoglobin of the light erythrocytes was reduced in the second and third trimesters (3.42% +/- 0.62% [mean +/- SD] [n = 306] in the first trimester, 2.15% +/- 0.48% [n = 353] in the second, and 2.06% +/- 0.58% [n = 300] in the third), and dense erythrocytes were higher in the third trimester (first 4.59% +/- 0.46%, second 4.70% +/- 0.49%, third 5.29% +/- 0.73%). Glycated albumin and fructosamine followed a pattern similar to the light erythrocytes. The group with abnormal glucose tolerance had significantly higher levels of glycated hemoglobin of the light erythrocytes in the first and third trimesters and glycated hemoglobin of the dense erythrocytes and glycated albumin in all trimesters.

CONCLUSION

The biphasic change in nonfractionated glycated hemoglobin is the sum of the lower glycated hemoglobin of the light erythrocytes and the higher glycated hemoglobin of the dense erythrocytes in late pregnancy. The stable glycated hemoglobin of fractionated erythrocytes and the glycated albumin accurately reflect maternal glucose metabolism during pregnancy.

Clinical evaluation of serum fructosamine in monitoring elderly outpatient diabetics

Recently, new serum glycated protein assays (ie, serum fructosamine) have been developed. Fructosamine assays objectively monitor short-term glycemic control and, when used in conjunction with HgA1C, enhance the clinical information obtained and greatly aid in the clinical management of diabetes. Because they rely on glycation of serum proteins, the clinical utility of these assays in the elderly may be altered secondary to the hypoproteinemia that often is seen in these states. Therefore, we investigated the role of glycated serum proteins (ie, fructosamine level) in monitoring elderly diabetics over a 4-month period of observation. We found that the fasting blood glucose over the 4-month period correlated well with the serum fructosamine activity (r = 0.79, P less than .001) and HgA1C (r = 0.78, P less than .001). In addition, we found that the mean daily glucose, as determined by outpatient monitoring, correlated well to both the fructosamine activity (r = 0.66, P less than .001) and HgA1C (r = 0.74, P less than .001). We found no effect on the measurement of the fructosamine assay by the level of albumin seen in these patients. Our study suggests that serum fructosamine and HgA1C are equally effective in monitoring the elderly patient, as has been established in the younger diabetic, and no correction need be made in the fructosamine assay to compensate for variable serum protein levels seen clinically in the elderly.

High-performance liquid chromatographic assay of serum glycated albumin

A method for determination of serum glycated albumin by high-performance liquid chromatography is presented. The system involves anion exchange chromatography to separate albumin and consecutive boronate affinity chromatography to separate glycated and nonglycated albumin. The method is rapid (20 min), precise (coefficient of variation, 0.7-4.9%), requires only a small sample (5 microliters), and can be automated. Assay of glycated albumin by this method is not influenced by the protein concentration of the sample or the presence of glucose. The variation in glycated albumin values in consecutive samples obtained within a day from diabetic patients (coefficient of variation, 2.02 +/- 0.65%) was significantly smaller (p less than 0.001) than that of values for fructosamine (coefficient of variation, 4.33 +/- 2.0%). The values of glycated albumin in normal subjects (20.2 +/- 1.6%) were clearly less than those in diabetic patients [39.6 +/- 5.4% in 40 Type 1 (insulin-dependent) and 39.4 +/- 5.9% in 25 Type 2 (non-insulin-dependent) patients]. The serum glycated albumin level was well correlated with HbA1c in 65 diabetic patients (r = 0.60). Because the life span of albumin in the circulation is short, measurement of glycated albumin should be useful as a short-term index of glycaemic control.