Glycosylated haemoglobin in renal failure

Predicting Blood Glucose Concentration after Short-Acting Insulin Injection Using Discontinuous Injection Records

Diabetes is an increasingly common disease that poses an immense challenge to public health. Hyperglycemia is also a common complication in clinical patients in the intensive care unit, increasing the rate of infection and mortality. The accurate and real-time prediction of blood glucose concentrations after each short-acting insulin injection has great clinical significance and is the basis of all intelligent blood glucose control systems. Most previous prediction methods require long-term continuous blood glucose records from specific patients to train the prediction models, resulting in these methods not being used in clinical practice. In this study, we construct 13 deep neural networks with different architectures to atomically predict blood glucose concentrations after arbitrary independent insulin injections without requiring continuous historical records of any patient. Using our proposed models, the best root mean square error of the prediction results reaches 15.82 mg/dL, and 99.5% of the predictions are clinically acceptable, which is more accurate than previously proposed blood glucose prediction methods. Through the re-validation of the models, we demonstrate the clinical practicability and universal accuracy of our proposed prediction method.

Information and consensus document for the detection and management of chronic kidney disease

Chronic kidney disease (CKD) is a major public health problem worldwide that affects more than 10% of the Spanish population. CKD is associated with high comorbidity rates, poor prognosis and major consumption of health system resources. Since the publication of the last consensus document on CKD seven years ago, little evidence has emerged and few clinical trials on new diagnostic and treatment strategies in CKD have been conducted, apart from new trials in diabetic kidney disease. Therefore, CKD international guidelines have not been recently updated. The rigidity and conservative attitude of the guidelines should not prevent the publication of updates in knowledge about certain matters that may be key in detecting CKD and managing patients with this disease. This document, also prepared by 10 scientific associations, provides an update on concepts, clarifications, diagnostic criteria, remission strategies and new treatment options. The evidence and the main studies published on these aspects of CKD have been reviewed. This should be considered more as an information document on CKD. It includes an update on CKD detection, risk factors and screening; a definition of renal progression; an update of remission criteria with new suggestions in the older population; CKD monitoring and prevention strategies; management of associated comorbidities, particularly in diabetes mellitus; roles of the Primary Care physician in CKD management; and what not to do in Nephrology. The aim of the document is to serve as an aid in the multidisciplinary management of the patient with CKD based on current recommendations and knowledge.

Effect of Correction of Hyperthyroidism with Anti-thyroid Drugs on the Glycated Hemoglobin in Non-diabetic Patients with Primary Hyperthyroidism

BACKGROUND

Glycated hemoglobin (HbA1c) levels are dependent not only on the average blood glucose levels over the preceding 2 - 3 months but also on the turnover of erythrocytes. Hyperthyroidism is known to be associated with an increase in erythrocyte turnover that may falsely lower the HbA1c in relation to the level of glycemia.

OBJECTIVES

To assess the impact of medical correction of hyperthyroidism on HbA1c, independent of changes in the fasting plasma glucose and 2-hour post-oral glucose tolerance test plasma glucose.

METHODS

Adult patients with overt hyperthyroidism (n = 36) were tested for their hemoglobin, reticulocyte percentage, HbA1c and fasting and post-oral glucose tolerance test (OGTT) 2-hour plasma glucose, both at baseline and following at least three months of near normalization of serum thyroxin on Carbimazole treatment.

RESULTS

Correction of hyperthyroidism in 36 patients was associated with an increase in the hemoglobin (P = 0.004) and a rise in HbA1c (P = 0.025), even though no significant change was observed in both the fasting (P = 0.28) and post OGTT two-hour plasma glucose (P = 0.54). Also, the proportion of patients with HbA1c ≥ 5.7% rose from 3/36 to 10/36; P = 0.016, while the proportion of patients with either abnormal fasting or abnormal post OGTT 2-hour plasma glucose or both did not show any significant change (P = 0.5). The sensitivity of HbA1c to diagnose prediabetes increased from 20% to 50% post- treatment.

CONCLUSIONS

Glycated hemoglobin is falsely low in relation to glycemia in patients with untreated hyperthyroidism.

Management of the Diabetic Patients with End Stage Renal Disease

Twenty diabetics with end-stage renal disease who had never previously received dialysis treatment were treated with continuous ambulatory peritoneal dialysis for periods of two to 36 months (average, 14.5). Intraperitoneal administration of insulin achieved good control of blood sugar Even though creatinine clearance decreased significantly (P = 0.001), contro of blood urea nitrogen and serum creatinine was adequate. Hemoglobin and serum albumin levels increased significantly (P = 0.005 and 0.04 respectively). Similarly, there was a significant increase in serum triglycerides and alkaline phosphatase (P = 0.02 and 0.05). Blood pressure became normal without medications in all but one of the patients. Retinopathy, neuropathy, and osteodystrophy remained unchanged. Peritonitis developed once in every 20.6 patient-months a rate similar to that observed in nondiabetics. The calculated survival rate was 92 per cent at one year; the calculated rate of continuation on ambulatory peritoneal dialysis was 87 per cent.

Systematic Review and Meta-Analysis of the Effects of Soy on Glucose Metabolism in Patients with Type 2 Diabetes

OBJECTIVE

This study aimed to assess the effects of soy consumption on glucose metabolism in patients with type 2 diabetes.

METHODS

A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Review (PRISMA) principles. Literature published between 1990 and 2019 was searched. Primary outcomes were the effect of soy on fasting plasma glucose (FPG), insulin, and HbA1c. The data were pooled using random effects models. Heterogeneity was assessed using Cochran's Q and I2 statistics. Also, the Cochrane Collaboration's tool for assessing risk of bias was used, and sensitivity analysis and meta-regression were conducted. Publication bias was evaluated using Egger and Begg tests.

RESULTS

Sixteen randomized clinical trials (RCTs) with a total of 471 participants were regarded as eligible and included in the study. Soy consumption had no significant effects on FPG, insulin, and HbA1c. After the "trim-and-fill" method was applied, soy revealed a significant effect size on FPG (adjusted Cohen's d: -0.18; p = 0.03). Also, subgroup analyses using studies with parallel design showed a significant improvement (moderate effect size) in FPG and insulin. Sensitivity analysis indicated the robustness of our findings. Among secondary outcomes, the results showed a significant effect of soy on HOMA-IR and total cholesterol levels.

CONCLUSIONS

Although this systematic review and meta-analysis indicated no beneficial effects of soy consumption on FPG, insulin, and HbA1c in patients with type 2 diabetes, pooling of parallel studies showed different results from crossover studies. The quality of evidence revealed low levels of confidence for primary outcomes. Therefore, further research is recommended.

Influence of iron deficiency on Hb A1c levels in type 2 diabetic patients

AIMS

Hemoglobin A1c (HbA1c) is gold-standard for the assessment of glycemic control in diabetic patients. Previous studies have reported that iron deficiency may elevate A1c concentrations, independent of glycemia. This study aimed to analyze the effect of iron status on HbA1c levels in diabetic patients.

METHODS

661 patients 336 females (228 menopausal and 108 premenopausal) and 325 males (237 age> 50 years and 88 age < 50 years) were recruited. HbA1c, ferritin, fasting plasma glucose, hemogram and medical history were recorded. Analysis of variance ANOVA and Pearson's regression were applied.

RESULTS

patients were divided according gender, age, glycemia and iron status (normal, latent iron deficiency LID, iron deficiency anemia IDA).All groups presented increasing HbA1c values in parallel with iron deficiency, subclinical and anemia, but the level of significance was not homogeneous in the different groups. Controlled premenopausal women HbA1c in normal iron status and IDA groups P = 0.0048, between normal and LID, P = 0.033. Not controlled premenopausal women Normal group and IDAP < 0.001, normal iron status and LID P = 0.019. Controlled menopausal women normal group and IDAP < 0.0001, LID and IDA P = 0.01. Not controlled menopausal women normal group and IDA P = 0.04. Controlled men over 50 years normal and IDA groups P = 0.002, LID and IDA P = 0.02. Controlled young men normal group and LID P = 0.03.

CONCLUSION

This study found a positive correlation between iron deficiency and increased HA1c levels. In diabetic patients with IDA should be interpreted with caution, due to the possibility of spurious increment in HbA1c.

Challenges in diagnosing and monitoring diabetes in patients with chronic liver diseases

The prevalence and mortality of diabetes mellitus and liver disease have risen in recent years. The liver plays an important role in glucose homeostasis, and various chronic liver diseases have a negative effect on glucose metabolism with the consequent emergence of diabetes. Some aspects related to chronic liver disease can affect diagnostic tools and the monitoring of diabetes and other glucose metabolism disorders, and clinicians must be aware of these limitations in their daily practice. In cirrhotic patients, fasting glucose may be normal in up until 23% of diabetes cases, and glycated hemoglobin provides falsely low results, especially in advanced cirrhosis. Similarly, the performance of alternative glucose monitoring tests, such as fructosamine, glycated albumin and 1,5-anhydroglucitol, also appears to be suboptimal in chronic liver disease. This review will examine the association between changes in glucose metabolism and various liver diseases as well as the particularities associated with the diagnosis and monitoring of diabetes in liver disease patients. Alternatives to routinely recommended tests will be discussed.

Origin of Glycosylated Hemoglobin Al in Chronic Renal Failure

In chronic renal failure both HbAI and HbAlc levels have been reported to be elevated. In order to investigate the causes of such increase we measured HbAI (cation-exchange chromatography), blood urea nitrogen, arterial blood pH, plasma bicarbonate, phosphatemia, serum iron and serum ferritin before dialysis in 60 uremic patients receiving long term hemodialysis. The increased levels of HbAI do not correlate with glucose intolerance, phosphatemia, blood urea nitrogen, time averaged concentration of urea, serum iron and serum ferritin. On the contrary the presence of a highly significant correlation between HbAI and arterial blood pH (p < 0.001) and between HbAI and plasma bicarbonate (p < 0.001) seems to emphasize a major role for acidosis in increasing the HbAI levels in uremic patients on long term hemodialysis.

[Consensus document for the detection and management of chronic kidney disease]

La enfermedad renal crónica (ERC) es un importante problema de salud pública que puede afectar en sus diferentes estadios a cerca del 10% de la población española y que supone una elevada morbimortalidad, así como un importante consumo de recursos al Sistema Nacional de Salud. Diez sociedades científicas involucradas en el manejo del paciente renal nos hemos puesto de acuerdo para hacer una puesta al día del anterior documento de consenso sobre ERC de 2007. El presente es la edición abreviada del documento general extenso, que puede ser consultado en las páginas Web de cada una de las sociedades firmantes. Contiene los siguientes aspectos: definición, epidemiología y factores de riesgo de la ERC; criterios de diagnóstico, evaluación y estadificación de la ERC, albuminuria y estimación del filtrado glomerular; concepto y factores de progresión; criterios de derivación a nefrología; seguimiento del paciente, actitudes y objetivos por especialidad; prevención de la nefrotoxicidad; detección del daño cardiovascular; actitudes, estilo de vida y tratamiento: manejo de la hipertensión arterial, dislipidemia, hiperglucemia, tabaquismo, obesidad, hiperuricemia, anemia, alteraciones del metabolismo mineral y óseo; seguimiento coordinado por atención primaria-otras especialidades-nefrología; manejo del paciente en tratamiento renal sustitutivo, hemodiálisis, diálisis peritoneal y trasplante renal; tratamiento paliativo de la uremia terminal. Esperamos que sirva de gran ayuda en el manejo multidisciplinar del paciente con ERC, a la vista de las recomendaciones más actualizadas.

[Consensus document for the detection and management of chronic kidney disease]

Chronic kidney disease (CKD) is an important global health problem, involving to 10% of the Spanish population, promoting high morbidity and mortality for the patient and an elevate consumption of the total health resources for the National Health System. This is a summary of an executive consensus document of ten scientific societies involved in the care of the renal patient, that actualizes the consensus document published in 2007. The central extended document can be consulted in the web page of each society. The aspects included in the document are: Concept, epidemiology and risk factors for CKD. Diagnostic criteria, evaluation and stages of CKD, albuminuria and glomerular filtration rate estimation. Progression factors for renal damage. Patient remission criteria. Follow-up and objectives of each speciality control. Nephrotoxicity prevention. Cardio-vascular damage detection. Diet, life-style and treatment attitudes: hypertension, dyslipidaemia, hyperglycemia, smoking, obesity, hyperuricemia, anemia, mineral and bone disorders. Multidisciplinary management for Primary Care, other specialities and Nephrology. Integrated management of CKD patient in haemodialysis, peritoneal dialysis and renal transplant patients. Management of the uremic patient in palliative care. We hope that this document may be of help for the multidisciplinary management of CKD patients by summarizing the most updated recommendations.

A history of HbA1c through Clinical Chemistry and Laboratory Medicine

HbA(1c) was discovered in the late 1960s and its use as marker of glycemic control has gradually increased over the course of the last four decades. Recognized as the gold standard of diabetic survey, this parameter was successfully implemented in clinical practice in the 1970s and 1980s and internationally standardized in the 1990s and 2000s. The use of standardized and well-controlled methods, with well-defined performance criteria, has recently opened new directions for HbA(1c) use in patient care, e.g., for diabetes diagnosis. Many reports devoted to HbA1c have been published in Clinical Chemistry and Laboratory Medicine (CCLM) journal. This review reminds the major steps of HbA(1c) history, with a special emphasis on the contribution of CCLM in this field.

[Treatment of type 2 diabetes mellitus in patients with chronic kidney disease. Grupo de Trabajo para el Documento de Consenso sobre el tratamiento de la diabetes tipo 2 en el paciente con enfermedad renal crónica]

Chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM) are highly prevalent chronic diseases, which represent an important public health problem and require a multidisciplinary management. T2DM is the main cause of CKD and it also causes a significant comorbidity with regard to non-diabetic nephropathy. Patients with diabetes and kidney disease represent a special risk group as they have higher morbi-mortality as well as higher risk of hypoglycemia than diabetic individuals with a normal kidney function. Treatment of T2DM in patients with CKD is controversial because of the scarcity of available evidence. The current consensus report aims to ease the appropriate selection and dosage of antidiabetic treatments as well as the establishment of safety objectives of glycemic control in patients with CKD.

Decreased serum glucose and glycosylated hemoglobin levels in patients with Chuvash polycythemia: a role for HIF in glucose metabolism

In Chuvash polycythemia, a homozygous 598C>T mutation in the von Hippel-Lindau gene (VHL) leads to an R200W substitution in VHL protein, impaired degradation of α-subunits of hypoxia-inducible factor (HIF)-1 and HIF-2, and augmented hypoxic responses during normoxia. Chronic hypoxia of high altitude is associated with decreased serum glucose and insulin concentrations. Other investigators reported that HIF-1 promotes cellular glucose uptake by increased expression of GLUT1 and increased glycolysis by increased expression of enzymes such as PDK. On the other hand, inactivation of Vhl in murine liver leads to hypoglycemia associated with a HIF-2-related decrease in the expression of the gluconeogenic enzyme genes Pepck, G6pc, and Glut2. We therefore hypothesized that glucose concentrations are decreased in individuals with Chuvash polycythemia. We found that 88 Chuvash VHL ( R200W ) homozygotes had lower random glucose and glycosylated hemoglobin A1c levels than 52 Chuvash subjects with wild-type VHL alleles. Serum metabolomics revealed higher glycerol and citrate levels in the VHL ( R200W ) homozygotes. We expanded these observations in VHL ( R200W ) homozygote mice and found that they had lower fasting glucose values and lower glucose excursions than wild-type control mice but no change in fasting insulin concentrations. Hepatic expression of Glut2 and G6pc, but not Pdk2, was decreased, and skeletal muscle expression of Glut1, Pdk1, and Pdk4 was increased. These results suggest that both decreased hepatic gluconeogenesis and increased skeletal uptake and glycolysis contribute to the decreased glucose concentrations. Further study is needed to determine whether pharmacologically manipulating HIF expression might be beneficial for treatment of diabetic patients.

Effect of iron deficiency anemia on hemoglobin A1c levels

BACKGROUND

Iron deficiency anemia is the most common form of anemia in India. Hemoglobin A1c (HbA1c) is used in diabetic patients as an index of glycemic control reflecting glucose levels of the previous 3 months. Like blood sugar levels, HbA1c levels are also affected by the presence of variant hemoglobins, hemolytic anemias, nutritional anemias, uremia, pregnancy, and acute blood loss. However, reports on the effects of iron deficiency anemia on HbA1c levels are inconsistent. We conducted a study to analyze the effects of iron deficiency anemia on HbA1c levels and to assess whether treatment of iron deficiency anemia affects HbA1c levels.

METHODS

Fifty patients confirmed to have iron deficiency anemia were enrolled in this study. HbA1c and absolute HbA1c levels were measured both at baseline and at 2 months after treatment, and these values were compared with those in the control population.

RESULTS

The mean baseline HbA1c level in anemic patients (4.6%) was significantly lower than that in the control group (5.5%, P<0.05). A significant increase was observed in the patients' absolute HbA1c levels at 2 months after treatment (0.29 g/dL vs. 0.73 g/dL, P<0.01). There was a significant difference between the baseline values of patients and controls (0.29 g/dL vs. 0.74 g/dL, P<0.01).

CONCLUSIONS

In contrast to the observations of previous studies, ours showed that HbA1c levels and absolute HbA1c levels increased with treatment of iron deficiency anemia. This could be attributable to nutritional deficiency and/or certain unknown variables. Further studies are warranted.

Inter-day glycemic variability assessed by continuous glucose monitoring in insulin-treated type 2 diabetes patients on hemodialysis

BACKGROUND

Type 2 diabetes patients on chronic hemodialysis have a high prevalence of cardiovascular complications and often show a poor glycemic control. Single-spot glycemic measurements are not always meaningful, and the hemoglobin A1c (HbA1c) value does not reflect short-term variations in glucose metabolism in this patient category. Therefore, to better understand their metabolic balance, we studied a group of diabetes patients on hemodialysis by a continuous glucose monitoring (CGM) system.

METHODS

Twelve insulin-treated type 2 diabetes patients on hemodialysis were studied by a microdialysis-based subcutaneous glucose sensor over a period of 2 days, including the dialysis day (HD) and the following inter-dialytic period ("free" day [FD]).

RESULTS

The mean 24-h glycemic value, the mean amplitude of glucose excursions, and the SD of mean glucose were significantly higher in the HD than the FD (186 ± 50 vs. 154 ± 25 mg/dL, P<0.05; 75 ± 22 vs. 56 ± 15 mg/dL, P<0.05; and 57 ± 6 vs. 35 ± 11 mg/dL, P<0.05, respectively). Considering the 48-h recording, there was a direct correlation between the mean glucose concentration and the HbA1c (r=0.47, P<0.05), whereas no association was observed between the measures of glucose variability and HbA1c.

CONCLUSIONS

Insulin-treated diabetes patients on hemodialysis showed different glucose profiles between the HD and the FD. In particular, in the HD they have had an increased glycemic variability, which may represent an adjunctive risk factor for cardiovascular complications. Therefore the use of a CGM system, as a means of assessing the measures of glycemic variability, could improve the management of insulin therapy in these patients.

Glycemic control and the risk of death in 1,484 patients receiving maintenance hemodialysis

BACKGROUND

It is controversial whether tighter glycemic control is associated with better clinical outcomes in people with kidney failure. We aim to determine whether worse glycemic control, measured using serum glucose and hemoglobin A(1c) (HbA(1c)) levels, is independently associated with higher mortality in patients undergoing maintenance hemodialysis.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

1,484 patients starting maintenance hemodialysis therapy in Alberta, Canada, between 2001 and 2007.

PREDICTOR

Serum glucose and HbA(1c) levels.

OUTCOME

All-cause mortality.

MEASUREMENTS

Monthly casual glucose levels from specimens drawn immediately before the first dialysis treatment were averaged over 3 months before and after hemodialysis therapy initiation. Similarly, monthly HbA(1c) values in patients with or at risk of diabetes were averaged.

RESULTS

Overall, median age was 66 years, 41% were women, 75% were white, and 55% had diabetes. All-cause mortality during 8 years (median, 1.5 years) was 43%; it was 49% in those with diabetes. There was no relation between average glucose level and mortality in unadjusted analysis (HR, 1.00 per 18 mg/dL [1 mmol/L]; P = 0.4) or after adjustment for confounders (HR, 0.98 per 18 mg/dL; 95% CI, 0.96-1.01; P = 0.2). Higher HbA(1c) level was not associated with mortality when analyzed in the unadjusted analysis (HR, 1.01 per 1% HbA(1c); P = 0.9) or after adjustment for confounders (HR, 0.98 per 1% HbA1c; 95% CI, 0.88-1.08; P = 0.7). Results were similar when HbA(1c) values were divided into prespecified categories (adjusted P > 0.6 for trend). Markers of malnutrition-inflammation (albumin, hemoglobin, and white blood cell values) or the presence of diabetes did not influence the relation between glycemic control and death (all P for interaction > 0.2).

LIMITATIONS

Registry data; casual serum glucose measurements; HbA(1c) values available for only a subset of participants.

CONCLUSIONS

Higher casual glucose and HbA(1c) levels were not associated with mortality in maintenance hemodialysis patients with or without diabetes. This may have implications for recommended glycemic targets, quality indicators, and how best to assess glycemic control in this high-risk population.

Metabolic and blood pressure monitoring in diabetic renal failure

In a prospective study of eight patients with type I diabetic renal failure, metabolic and blood pressure monitoring was evaluated during progression to end-stage renal disease (ESRD). The mean observation time was 37 months. The mean glomerular filtration rate (GFR) fell significantly (from 33 to 16 ml/min) implying a mean deterioration rate of 0.57 ml/min/month. This rate showed significant correlation with mean arterial blood pressure at out-patient observations, but not with blood glucose monitored as 24-hour profile or with glycosylated hemoglobin. Patients with growth hormone values within the upper limit of the normal range showed faster decline of GFR than patients with low values. The study demonstrated that advanced diabetic renal failure may progress slowly to ESRD. The blood pressure pattern, but not blood glucose values, influenced significantly the deterioration rate of glomerular function.

Glucose tolerance in patients undergoing continuous ambulatory peritoneal dialysis

The effects of continuous ambulatory peritoneal dialysis (CAPD) on glucose tolerance and serum immunoreactive insulin and glucagon responses to oral glucose over the first year of therapy were studied in 13 uremic patients. Oral glucose tolerance tests were performed before treatment started, and again after 3 and 12 months on CAPD. Before CAPD, the patients showed decreased glucose tolerance. However, neither fasting blood glucose and serum insulin and glucagon levels nor the insulin and glucagon levels during the tests were significantly different from results obtained in 13 healthy controls. During CAPD, the mean intraperitoneal supply of glucose from the dialysates varied between 121 and 245 g/day and did not change during the study period. Glucose tolerance and hormone responses to glucose did not change during the study period. No patient developed manifest diabetes mellitus. We conclude that glucose intolerance in uremia persists during CAPD, but despite the continuous peritoneal absorption of 100-200 g of glucose during CAPD, the treatment had no effect on glucose tolerance and insulin secretory response.

Glycaemic control in type 2 diabetic patients on chronic haemodialysis: use of a continuous glucose monitoring system

BACKGROUND

The proportion of diabetic patients undergoing haemodialysis is rapidly increasing. Glucose control among such patients is difficult to assess. We aimed to evaluate the clinical performance of a continuous glucose monitoring system (CGMS) in type 2 diabetic patients on chronic haemodialysis.

METHODS

We used a 4-day CGMS to monitor glucose levels in 19 haemodialysed type 2 diabetic patients (HD T2) including 2 days with and 2 days without dialysis session, and 39 non-HD T2 in a double-centre study.

RESULTS

The glucose concentration according to the glucose meter and CGMS were correlated in HD T2 patients (r = 0.90, P < 0.0001) and in non-HD T2 patients (r = 0.81, P < 0.0001). The relative absolute difference (RAD) between glucose determined by a glucose meter and glucose determined by the CGMS did not differ between HD T2 and non-HD T2 patients (9.2 +/- 10.5 vs. 8.2 +/- 7.6%; P = 0.165). Glycated haemoglobin (A1c) and mean glucose concentration were strongly correlated in non-HD T2 patients (r = 0.71; P < 0.0001) but weakly correlated in HD T2 patients (r = 0.47; P = 0.042). Fructosamine was correlated with the mean glucose concentration in non-HD T2 (r = 0.67; P < 0.0001) but not in HD T2 patients (r = 0.04; P = 0.88).

CONCLUSION

CGM is a validated marker of glycaemic control in HD diabetic patients. This tool showed that A1c and fructosamine, despite being good markers of glycaemic control in non-HD diabetic patients, are of poor value in HD diabetic patients.

Review of hemoglobin A(1c) in the management of diabetes

Hemoglobin HbA(1c) (A(1c)) has been used clinically since the 1980s as a test of glycemic control in individuals with diabetes. The Diabetes Control and Complications Trial (DCCT) demonstrated that tight glycemic control, quantified by lower blood glucose and A(1c) levels, reduced the risk of the development of complications from diabetes. Subsequently, standardization of A(1c) measurement was introduced in different countries to ensure accuracy in A(1c) results. Recently, the International Federation of Clinical Chemists (IFCC) introduced a more precise measurement of A(1c) , which has gained international acceptance. However, if the IFCC A(1c) result is expressed as a percentage, it is lower than the current DCCT-aligned A(1c) result, which may lead to confusion and deterioration in diabetic control. Alternative methods of reporting have been proposed, including A(1c) -derived average glucose (ADAG), which derives an average glucose from the A(1c) result. Herein, we review A(1c) , the components involved in A(1c) formation, and the interindividual and assay variations that can lead to differences in A(1c) results, despite comparable glycemic control. We discuss the proposed introduction of ADAG as a surrogate for A(1c) reporting, review imprecisions that may result, and suggest alternative clinical approaches.

Indicators for blood glucose control in diabetics with end-stage chronic renal disease: GHb vs. glycated albumin (GA)

Diabetics with end-stage renal disease (ESRD) exhibit abnormal life span of erythrocytes, and thus, HbAlc is not necessarily a good indicator for blood glucose control. The present study was conducted to reaffirm this point and determine whether glycated albumin (GA) can be used instead of HbAlc. The following three groups of patients with diabetes served as subjects: 49 predialysis patients with ESRD (predialysis group), 37 patients with ESRD on dialysis (dialysis group), and 40 patients without nephropathy (non-dialysis group). The profile set mean blood glucose was calculated by measuring blood glucose levels seven times a day. The relationship of profile set mean blood glucose with HbAlc and GA levels was then investigated. Corrected HbAlc levels were calculated by applying the profile set mean blood glucose of each ESRD patient to the regression formula for the HbAlc of non-dialysis patients. The actual and corrected HbAlc levels for the predialysis patients were 5.4+/-1.1 and 7.9+/-1.1%, respectively, while those for the dialysis patients were 5.6+/-1.0 and 7.5+/-0.9%, respectively (p<0.0001). The changes in GA levels in relation to the blood glucose control in the dialysis patients matched those in non-dialysis patients. HbAlc levels for diabetics with ESRD were lower than indicated by their blood glucose control. When assessing blood glucose control based solely on HbAlc, erroneous results may be obtained. In such cases, GA may be used instead of HbAlc.

Evidence for the role of lipid peroxides on glycation of hemoglobin and plasma proteins in non-diabetic asthma patients

BACKGROUND

Collective evidences reveal that malondialdehyde (MDA), reduced glutathione (GSH) and ascorbic acid can modulate protein glycation. We investigated the concentrations of MDA, GSH, ascorbic acid and protein glycation in asthma patients to delineate the possible association among these parameters.

METHODS

Blood was collected from 18 asthma patients and 16 age and sex matched control subjects. Glycated hemoglobin (HbA1C), GSH, MDA, vitamin C, fructosamine and glucose were assessed in both groups. The effect of H2O2 on glycation of hemoglobin was studied by incubating normal healthy erythrocytes with either 5 or 50 mmol/l glucose concentration.

RESULTS

Plasma of asthma patients revealed significantly higher concentrations of lipid peroxides and fructosamine concentrations than the matched controls. Glycated hemoglobin concentrations were also found to be significantly increased. Ascorbic acid and GSH concentrations were decreased significantly in the test group when compared with the healthy control group. When the effects of fasting glucose, GSH and ascorbic acid on the concentrations of HbA1C and fructosamine were refuted by partial correlation analysis, MDA was found to be a significant determinant of HbA1c and fructosamine in patients with asthma. The in vitro model with human erythrocytes showed an enhancement of protein glycation by H2O2.

CONCLUSION

An increased glycation of proteins was found in asthma patients. These data also support the premise that lipid peroxides per se do have a role to play in glycation of hemoglobin and plasma proteins.

Reassessing the increased glycation of hemoglobin in nondiabetic chronic renal failure patients: a hypothesis on the role of lipid peroxides

BACKGROUND

Glycated hemoglobin (HbA(1C)) is considered clinically useful for assessing long-term integrated control of blood glucose in diabetes. However, an increased HbA(1C) concentration has been documented in chronic renal failure (CRF) patients without any history of diabetes. Collective evidences reveal that lipid peroxidation (MDA) can modulate protein glycation. We evaluated the relationship between glycated hemoglobin (HbA(1C)) and lipid peroxidation in non-diabetic CRF patients.

METHODS

Twenty-eight nondiabetic CRF and 23 age- and sex-matched healthy subjects were enrolled for this study. Plasma urea, creatinine, lipid peroxides, fasting glucose and HbA(1C) were analyzed in both the groups. The in-vitro effect of MDA on glycation of hemoglobin was studied by incubating healthy erythrocytes with either 5 or 50 mmol/l glucose concentration.

RESULTS

The percentage of HbA(1C) concentrations and plasma malondialdehyde (MDA) were significantly increased in CRF patients compared to control subjects. When the effects of uremia and blood glucose on the concentration of HbA(1C) was refuted by partial correlation analysis, MDA was found to be a significant determinant of HbA(1C) (r=0.41, p=0.04) in patients with renal failure. In-vitro incubation of RBC with glucose along with MDA was found to enhance the process of hemoglobin glycation.

CONCLUSION

Our results suggest that lipid peroxidation per se can contribute to glycation of hemoglobin, warranting extra-precaution in interpreting HbA(1C) as a measure of glycemic control in CRF.

Hemoglobin A1c levels in non-diabetic patients with end-stage renal disease (ESRD) receiving hemodialysis

Hemoglobin A1c (HbA1c) level represents an established tool to monitor glycemic control in diabetic patients, but the previous commonly used tests of HbA1c in patients with end-stage renal disease (ESRD) may not be reliable because of the presence of anemia, assay interference from uremia, and decreased red blood cell (RBC) life span. HbA1c level measured by turbidimetric immunoassay method is not affected by the above factors. We enrolled 40 non-diabetic ESRD patients receiving hemodialysis and 55 non-diabetic patients without ESRD for this study. HbA1c was analyzed by turbidimetric immunoassays with Synchron CX system. We found that the average HbA1c level in non-diabetic ESRD patients receiving hemodialysis was 5.99% and in the control group was 5.45% (p<0.05). There was no significant difference in fasting glucose levels and Hct % between the two groups (p>0.05). Our limited data indicate that HbA1c levels are elevated in nondiabetic ESRD patients receiving hemodialysis. We propose that the elevated HbA1c level may be due to the repetitive exposure of patients' RBCs to the high glucose level in dialysate (200 mg/dl) or may reflect true glucose intolerance in non-diabetic patients with ESRD.

Assessing glycemic control in patients with diabetes and end-stage renal failure

Blood glucose monitoring is important in optimizing long-term outcomes in diabetic patients. Reliance on near-patient testing and the use of longer term measures of glycation are the current cornerstones. However, as this review details, there are significant problems using blood tests as measures of metabolic control in uremic diabetic patients.

Haemoglobin A1c: Analysis and Standardisation

The measurement of glycated haemoglobin has become centrally important in the monitoring of glycaemic control in the patient with diabetes. A number of analytical techniques have been described to measure this important haemoglobin fraction, and the fraction measured depends on the technique used; this has resulted in laboratories reporting different fractions i.e., HbA1, HbA1c and total glycated haemoglobin. This paper outlines methods currently used in clinical laboratories for the measurement of this glycated fraction. It describes the principles behind these methods and goes on to describe the new IFCC reference method, which will be used in the future to standardise methods used in the clinical laboratory. Analytical goals and factors that interfere with methods are also discussed.

Glycated haemoglobin in various pathological conditions: investigations based on a new, fully automated method

A new automated affinity chromatographic method for determining glycated haemoglobin (GHb) in dogs and cats was tested. The method appeared to be practical, quick and accurate. The reference range, calculated on the basis of 50 healthy dogs and 43 healthy cats, lay between 2.4 and 3.4 per cent in dogs and 2.0 and 2.9 per cent in cats. Concentrations were not influenced by age or gender. GHb levels obtained for 21 dogs and 18 cats with newly diagnosed diabetes mellitus were significantly higher than those of the control animals, ranging from 4.5 to 8.6 per cent (median 6.1) in dogs and from 2.7 to 6.0 per cent (median 3.8 per cent) in cats. The GHb levels in 31 normoglycaemic dogs with anaemia ranged from 2.3 to 4.3 per cent (median 3.3 per cent), and those of 22 normoglycaemic cats with anaemia from 2.6 to 3.9 per cent (median 3.2 per cent); both sets of levels were significantly elevated compared to control group values. GHb concentrations in animals with polycythaemia, azotaemia or liver disease showed no significant deviations from the control group; in individual cases they were slightly elevated compared to the reference range. The automated measuring method employed can be used to determine GHb in dogs and cats. Anaemic animals should generally be excluded from the GHb determination.

Does uremia interfere with HbA1c results in the FPLC method with Mono S cation exchanger?

To study the effect of uremia on hemoglobin A1c determination by the Mono S FPLC method, samples from uremic patients, with and without diabetes, and controls, were analysed with a modified chromatography with enhanced resolution. Besides specific HbA1c, four minor peaks could be seen, included in routine HbA1c values. Two of these differed in concentration in the patient groups studied: a shoulder-like peak close to the specific HbA1c (S fraction) and a slightly less cationic minor peak (M fraction). Both S and M peaks were higher in uremic than in nonuremic subjects, but the M peak was associated more with diabetes. In the nondiabetic group, the mean routine HbA1c value was 0.8% units higher in uremic than nonuremic individuals. The specific HbA1c was nondependent on uremia. Thus, in uremic patients, there seems to be falsely elevated HbA1c values, mainly because of small interfering hemoglobin fractions, not specific HbA1c.

Chromatographic and electrophoretic methods for modified hemoglobins

The discovery of the clinically important glycohemoglobin adducts and their relation to diabetes mellitus have greatly stimulated the study of other minor post-translational modifications of hemoglobin. Chromatographic and electrophoretic procedures have played an important role in these studies. Today several hemoglobin adducts are known and the formation of adducts with glucose, phosphorylated carbohydrates, urea/cyanate, aspirin, vitamins, acetaldehyde, penicillin and acetyl CoA have been described. Furthermore, new adducts, such as those observed using hemoglobin as a biochemical marker monitoring environmental, occupational and lifestyle exposures to reactive toxic chemicals are constantly being reported. This review deals with chromatographic and electrophoretic separation methods available for the study of non-enzymatic post-translational modifications of hemoglobin. Suitability, perspectives and biomedical applications are discussed.

Adaptation of latex-enhanced assay for percent glycohemoglobin to a Dade Dimension® analyzer

At present no method for glycohemoglobin (%HbA1c) is automated on a main-line analyzer to allow joint measurement with other indicators of diabetic control such as glucose and cholesterol. We describe an adaptation of a latex-enhanced competitive immunoassay for quantifying %HbA1c to the Dade International Dimension® analyzer. After a manual hemolysis step, HbA1c and total hemoglobin (Hb) are determined separately. The concentration of glycated β-subunit is obtained from the immunoassay, whereas Hb is assessed colorimetrically from a derivatized form. Both reactions were fully optimized for accuracy, precision, and specificity on the Dimension; stabilities of reagents and calibration were established; and potential interferences were assessed. The analyzer gave reliable results over the required clinical range of 1–15% HbA1c. Within-run and total assay variation were within 5% of the target CV limits, as determined by ANOVA with three representative sample pools across 20 days. Close agreement with an established HPLC procedure and a commercially available enzyme immunoassay was observed for 140 samples from clinically defined patient groups. Additional samples from patients with hemoglobinopathies (n = 20) demonstrated a more complex relationship between methods. We conclude that adaptation of the method for use with the Dimension analyzer is a valid method for quantifying %HbA1c.

Carbamylated haemoglobin in normal, diabetic and uraemic patients

Carbamylated haemoglobin arises from the non-enzymic modification of haemoglobin monomers by isocyanate derived from the spontaneous dissociation of urea. We measured carbamylated haemoglobin by high performance liquid chromatography in healthy subjects, non-uraemic hospital patients, diabetics, and different groups of uraemic patients. Carbamylated haemoglobin levels were found to be raised in uraemic subjects, but were independent of age, sex, glycaemic state and haemodialysis procedure. There was no significant difference in carbamylated haemoglobin levels between two groups of patients having different modes of dialysis treatment, probably indicating a similar degree of uraemic exposure in these patients.

Retrospective glycemic status of diabetic patients: glycosylation of blood proteins in diabetes and chronic renal failure

In vivo and in vitro studies were carried out to evaluate the clinical application of glycosylated hemoglobin and plasma proteins in the diagnosis and management of diabetes mellitus. Glycosylated hemoglobin registered an almost 80% fall in diabetic patients following controlled glycemia for two months while glycosylated plasma protein level registered an 80% fall in the patients after fifteen days of blood glucose homeostasis. Human serum proteins were glycosylated in vitro and glycosylation was linearly proportional to the glucose concentration and incubation time. Polyacrylamide gel electrophoresis of glycosylated serum proteins revealed that albumin and transferrin are the major proteins that are significantly glycosylated. Glycosylated hemoglobin and plasma protein levels were also increased in chronic renal failure patients without any history of diabetes.

Impact of metabolic control in progression of clinical diabetic nephropathy

Renal clearance of 51Cr-EDTA as a measure of glomerular filtration rate was followed prospectively for 21 months in 18 Type 1 (insulin-dependent) patients with juvenile-onset diabetes and nephropathy. Hypertension was treated aggressively, attaining a mean blood pressure of 154/88 mmHg in the supine and 126/82 mmHg in the standing position. The mean glycosylated haemoglobin value (HbA1c) during the observation period was found to correlate well with the mean of random blood glucose values (r = 0.72). It also correlated to the rate of glomerular filtration rate decline over time, whether the latter was calculated as slope coefficient for all available data (r = -0.52, p less than 0.05) or based on the first and last observations only (r = -0.57, p less than 0.05). In a multiple linear stepwise regression analysis also including mean arterial blood pressure, the correlation between glomerular filtration rate decline and HbA1c was significant at p less than 0.01; this explained one-third of the progression, while mean arterial pressure could not be shown to contribute. It is concluded that hyperglycaemia, contrary to the general belief, is a risk factor for the progression of clinical diabetic nephropathy with reduced glomerular filtration rate.

Nonenzymatically glycosylated proteins

Nonenzymatic glycosylation takes place in all proteins with a free-reacting lysine or valine in the presence of glucose. The formation of glycosylated plasma albumin, hemoglobin (Hb A1c), and skin collagen provides a diagnostic index of short- to long-term time-concentration of glucose in vivo. A wide range of assay methods are available, with affinity chromatographic, isoelectric focusing, and spectrophotometric methods providing the best accuracy and versatility. Glycosylated hemoglobin assays indicate glucose pressure over the previous 2 to 3 months and are of diagnostic value in general diabetic control, while glycosylated plasma albumin determinations are preferable in acute episodes in the life of a diabetic (e.g., pregnancy, infection, stress, trauma, surgery), since they provide an overview of changing blood glucose values of the previous 2 to 4 weeks. Glycosylated collagen estimations reflect tissue aging and are relevant in healing processes. Glycosylation alters the biologic activity of proteins, and these may relate to the manifold complications concomitant on the lifelong elevation of blood and tissue glucose in the diabetic (C6a). Assays for glycosylated hemoglobin have been routinely performed in clinical chemistry laboratories for a decade, and convenient determination for other nonenzymatically glycosylated proteins is proceeding apace.

Continuous ambulatory peritoneal dialysis (CAPD) in diabetic patients with end-stage renal failure in Hong Kong

The authors' experience in managing 17 diabetic patients among their first 100 consecutive patients treated with continuous ambulatory peritoneal dialysis (CAPD) was reviewed. The diabetics were significantly older than the non-diabetics, but their biochemistry was comparable to that of the non-diabetics. With three exchanges a day, the requirement for antihypertensives was high (60%). Exit-site infection occurred at a rate of one episode per 9.7 patient-months, and the frequency of peritonitis averaged one episode per 9.4 patient-months; the main culprit was Staphylococcus pyogenes. Rehabilitation was good because the patients had to finance their treatment. In spite of old age, 23% worked full-time. There was no progressive increase in serum cholesterol or triglycerides. Glycemic control was good and was comparable whether the patients were given insulin subcutaneously or intraperitoneally. There was a highly significant (p less than 0.001) positive correlation between fasting blood glucose levels and HbA1 concentrations. Fasting blood glucose concentrations did not correlate with either serum cholesterol or triglyceride concentrations. Diabetic retinopathy progressed in five patients, to the point that their vision was severely impaired. There was no relationship between the degree of glycemic control and progression of diabetic retinopathy. Two patients died of cardiovascular causes, but there were no peritonitis-related deaths. Cummulative patient survival at 2 years was 86%, and the corresponding technique survival, 100%.

Glycosylated haemoglobin in uraemia

Glycosylated haemoglobin (GHb) was measured in 71 patients with stable chronic renal failure by the thiobarbituric acid (TBA) reaction and by agar gel electrophoresis. Nineteen patients were diabetic. Of the non-diabetics, 22 were treated conservatively (including 8 children), 15 by maintenance haemodialysis, and 15 by continuous ambulatory peritoneal dialysis. GHb measured by both methods correlated with postprandial blood glucose levels. There was a significant discrepancy between the two methods only in patients with serum urea concentrations greater than 30 mmol/l, mean +/- SD, (6.8 +/- 2.6% vs 8.2 +/- 2.5% for TBA and electrophoresis, respectively). This difference, delta GHb, correlated with serum urea, serum creatinine, and serum bicarbonate, but after logistic regression of results from all 71 patients only serum urea was associated with delta GHb. Lower haemoglobin and GHb and high fetal haemoglobin concentrations in the haemodialysis group suggested increased haemolysis in these patients. Measurement of GHb by the TBA method and by agar gel electrophoresis remain useful indicators of hyperglycaemia in patients with mild, stable chronic renal failure.

Nonenzymatically glucosylated serum proteins in patients with end-stage renal disease

We report here abnormally elevated levels of nonenzymatically glucosylated whole-serum proteins in nondiabetic, as well as diabetic patients with end-stage renal disease (ESRD). Increased glucosylation of serum proteins and structural proteins has been documented in patients with diabetes mellitus, but not previously in ESRD. Increased levels of hemoglobin A1 have been reported in patients with ESRD, but appear to be due to carbamylation of hemoglobin rather than glucosylation. Using an assay that does not detect carbamylation, the present study demonstrates abnormally elevated levels of nonenzymatically glucosylated whole-serum proteins in all the chronic hemodialysis and continuous ambulatory peritoneal dialysis (CAPD) patients studied. Further, we found no change in levels of these abnormal proteins when patients were changed from hemodialysis with a dialysate that contained no glucose to one that did, or to CAPD in which large amounts of glucose are absorbed from the dialysate. The mode of dialysis does not appear to affect glucosylated protein levels in ESRD.

Glucose tolerance test and glycosylated haemoglobin measurement for diagnosis of diabetes mellitus--an assessment of the criteria of the WHO Expert Committee on Diabetes Mellitus 1980

Fasting glycosylated haemoglobin was analysed in 535 consecutive patients having an oral 75 g glucose tolerance test for diagnostic purposes. A reference range for fasting glycosylated haemoglobin was established from patients with a non-diabetic glucose tolerance test as defined by the World Health Organisation Expert Committee on Diabetes Mellitus. The predictive value of a glycosylated haemoglobin of over 10.0% (mean normal +/- 3 SD) for detecting a diabetic glucose tolerance test was 89% but sensitivity was only 43%. A raised glycosylated haemoglobin is useful for confirming the diagnosis of diabetes mellitus in patients with long-standing hyperglycaemia but glycosylated haemoglobin is within the reference range in many patients with newly developed diabetes or other minor abnormalities of glucose tolerance. The glucose tolerance test must remain the test of choice in these patients.