A rapid automated method for measuring glycated haemoglobin on the Beckman CX7 analyser

Social and psychological characteristics of Kuwaiti children and adolescents with type 1 diabetes

Type 1 diabetes mellitus is a chronic disease that may have an impact on children's psychosocial adjustment. This study aimed to investigate the psychosocial characteristics of Kuwaiti children with type 1 diabetes as compared to healthy children without diabetes, and assess the impact of glycaemic control on psychosocial variables. A total of 349 school children aged 6-18 years with type 1 diabetes, and 409 children without diabetes having comparable age, gender, and social class were included in the study. Data were obtained by interviewing children and parents using a questionnaire. Psychological distress was measured by the Hopkins symptoms checklist-25 scale including anxiety and depression. Glycaemic control was assessed by glycosylated haemoglobin, HbA(IC) level. Glycaemic control was considered 'good to excellent' at HbA(IC)<8.0%, 'fair' at HbA(IC) 8.1 to 10.0%, and 'poor' at HbA(IC)>10.0%. Median scores of anxiety, depression, and total distress were significantly higher in children with diabetes indicating worse psychological adjustment. There was also significant difference between children with diabetes and those without diabetes in social aspects and school absence days. There was significant positive correlation between HbA(IC) concentration and scores of the psychological functioning indices. Children with poor glycaemic control had worse psychological adjustment. After controlling the variance accounted by gender and age, stepwise multiple regression analysis showed that girls, older children, children in need of emotional support, and those with higher HbA(IC) were at higher risk for psychological maladjustment. These variables explained 47.9% of the variation in total distress. In conclusion, the study supported our hypotheses. Children with diabetes had worse psychological adjustment, and distress was related to glycaemic control. Since psychological distress increases the risk for future complications due to its relation with glycaemic control, longitudinal studies are recommended to identify children with diabetes having distress at an early stage when preventive interventions are effective.

Lipoprotein(a) and Other Cardiovascular Metabolic Risk Factors in Kuwaiti Children with Type-1 Diabetes

BACKGROUND/AIMS

Lipoprotein(a) synthesis and catabolism could be influenced by insulin or by diabetes metabolic complications in patients with type-1 diabetes. The aim of the study was to investigate the relation of plasma lipoprotein(a) concentrations with metabolic cardiovascular risk factors in Kuwaiti children with uncomplicated type-1 diabetes.

METHODS

This case-control study included 115 (44 males and 71 females) diabetic children aged 6-18 years matched by age and sex to 115 non-diabetic children as controls.

RESULTS

There was no significant difference between the mean lipoprotein(a) concentrations in type-1 diabetic children (27.34 mg/dl) and their controls (22.80 mg/dl). Total cholesterol, apolipoprotein A1 and B levels were significantly higher in diabetic children than controls. In diabetic children, significant correlations were found between lipoprotein(a) levels and glycated hemoglobin (r = 0.249, p = 0.011), total cholesterol (r = 0.208, p = 0.025), and apolipoprotein B (r = 0.349, p < 0.001). The proportion of diabetic children with lipoprotein(a) >30 mg/dl was significantly higher in those having poor glycemic control (glycated hemoglobin >9.0%, p = 0.013), raised total cholesterol (p = 0.033), or with a family history of cardiovascular disease (p = 0.006).

CONCLUSION

Plasma lipoprotein(a) levels were not elevated in young type-1 diabetic children compared to non-diabetic controls; however, lipoprotein(a) levels were significantly higher in diabetic children with poor glycemic control. Moreover, there were significant correlations between lipoprotein(a) and the metabolic cardiovascular risk factors total cholesterol, atherogenic index, apolipoprotein B and apolipoprotein B/A1 ratio.

Angiotensin-converting enzyme gene polymorphism and lipid profiles in Kuwaiti children with type 1 diabetes

METHODS

We studied angiotensin-converting enzyme (ACE) gene polymorphism and lipid profiles in Kuwaiti children with uncomplicated type 1 diabetes. A total of 125 children with type 1 diabetes were matched in a case-control study on age and gender to 125 non-diabetic children as controls. Serum lipids (total cholesterol, TC; high-density lipoprotein cholesterol, HDL; low-density lipoprotein cholesterol, LDL-c; triglycerides, TG; apolipoprotein A1 and B, apo A1 and B; lipoprotein(a), Lp(a)); and glycated hemoglobin, HbA1c were evaluated according to ACE genotypes.

RESULTS

Genotype distributions were found to be similar in cases [ACE insertion/insertion (II) 9.6%, ACE insertion/deletion (ID) 38.4%, ACE deletion/deletion (DD) 52.0%], and controls (II 8.8%, ID 43.2%, DD 48.0%), and were characterized by higher frequencies of DD, ID, and lower frequencies of II. Diabetic children with DD genotype showed significantly higher levels of TC (p < 0.01), HDL (p < 0.001), and apo A1 (p < 0.001) than controls. There was a higher proportion of diabetic children with family history of cardiovascular disease (CVD) in the DD genotype group (51.9%) than those with II genotype group (11.1%) (p < 0.001). Also, there was a significant increase in the frequency of diabetic children with Lp(a) > 30 mg/dL in children with a family history of CVD (p = 0.008). Lp(a) levels were correlated with HbA1c in the diabetic group (r = 0.239, p = 0.019), but when patients with poor glycemic control (HbA1c > 9%) were excluded, the significant correlation disappeared (r = 0.127, p = 0.381). After adjusting confounding between variables, the logistic regression analysis showed that the two significantly related variables with the rise in Lp(a) were increasing TC level and poor glycemic control.

CONCLUSIONS

In children with type 1 diabetes, the role of ACE polymorphism as a probable contributor to CVD seems to be partially mediated through other factors such as poor glycemic control, TC, and Lp(a) level. A longitudinal study is recommended with a larger number of patients in each ACE genotype group in order to assess such associations.

Association of serum sialic acid with cardiovascular metabolic risk factors in Kuwaiti children and adolescents with type 1 diabetes

The aim of the present study was to investigate the relation of serum total sialic acid (TSA) concentrations with cardiovascular metabolic risk factors in Kuwaiti children and adolescents with uncomplicated type 1 diabetes. This case-control study included 150 (57 males and 93 females) type 1 diabetic children aged 6 to 18 years matched by age and sex to 150 nondiabetic children as controls. Measured variables included weight, height, systolic, diastolic blood pressure, and biochemical variables: blood glucose, glycated hemoglobin (HbA(1C)), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), apolipoproteins (apo) A1 and B, and urine microalbumin. There was no significant difference between mean serum TSA of the type 1 diabetic children (671.0 mg/L) and their controls (663.7 mg/L). In diabetic children, mean serum TSA was significantly higher in females (699.1 mg/L) than in males (625.2 mg/L) (P =.003). Significant correlations were found between serum TSA and the cardiovascular risk factors TC (P =.002), TG (P <.001), and apo B (P =.008). TSA mean level was significantly higher in diabetic children with poor glycemic control (HbA(1C) > 9.0%; P =.015), raised TC (P =.013), raised TG (P =.014), and in children with family history of cardiovascular disease (CVD; P =.02). In conclusion, the study suggests that serum TSA levels were not elevated in young type 1 diabetic children as compared with controls. The study also confirmed significant correlation of TSA concentrations with CVD risk factors TC, TG, and apo B, and as such serum TSA may be considered as a marker for CVD risk, especially in diabetic patients. A long-term prospective study is recommended to ascertain the longitudinal relationship of serum TSA with the adverse metabolic changes in type 1 diabetic children as complications prevail.

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.

Detection of HbA(1c) by boronate affinity immunoassay using bacterial magnetic particles

We have developed a boronate affinity immunoassay system using m-aminophenylboronic acid (mAPB) coupling to bacterial magnetic particles (BMPs). Homobifunctional crosslinker, Bis-(succcimidyl)suberate (BS3), was employed for preparation of mAPB-BMPs conjugates (mAPB-BMPs). Quantities of HbA(1c) on mAPB-BMPs were evaluated based on luminescence from alkaline phosphatase-conjugated anti-Hb antibody (ALP-antibody) binding to HbA(1c) on the BMP surface. The binding of HbA(1c) to mAPB-BMPs occurred gradually and was almost completed within 10 mm. The coupling reaction is enhanced due to static electric interaction between the positive charges on HbA(1c) and negative charges on BMPs. The amount of HbA(1c) binding to mAPB-BMPs increased with increasing sodium chloride concentrations in the range of 0-100 mM. However, the amount of Hb binding to mAPB-BMPs also increased in high concentration of sodium chloride. The Hb binding to mAPB-BMPs was detached from mAPB-BMPs when Hb-mAPB-BMPs were washed with low salt buffer. This indicates that Hb is nonspecifically adsorbed onto the surface of mAPB-BMPs in high concentration of sodium chloride. These results suggest that selective separation of HbA(1c) using mAPB-BMPs can be achieved with these conditions. A dose-response curve was obtained between luminescence intensity and HbA(1c) concentration using a fully automated boronate affinity immunoassay. A linear relationship between luminescence intensity and HbA(1c) concentration was obtained in the range of 10-10(4) ng/ml.

A comparison of automated fructosamine and HbA1c methods for monitoring diabetes in pregnancy

Two automated methods for measuring fructosamine (Test Plus and the original fructosamine assay) and glycated haemoglobin (Tina-quant immunoassay) were compared to determine which is the best index of blood glucose control during pregnancy. Thirteen women with type 1 diabetes were studied, with four-weekly measurements of HbA1c and fructosamine Test Plus using a Hitachi 911 analyser and fructosamine measured using an Olympus AU800 analyser. HbA1c correlated better (r = 0.573) with mean blood glucose (MBG) concentration than did fructosamine Test Plus (r = 0.347), even after correction for total protein concentration (r = 0.463), while there was no significant correlation with the original fructosamine method (r = 0.201). HbA1c correlated better with fasting/pre-prandial MBG concentrations, whereas fructosamine Test Plus correlated better with post-prandial MBG concentrations. Fructosamine Test Plus decreased with gestational age, and correlated with albumin and total protein concentrations, whereas HbA1c did not change with gestational age. Thus, HbA1c and fructosamine Test Plus were found to be useful in verifying home blood glucose measurements in diabetic pregnancy, with HbA1c being the best predictor of MBG concentration.

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.

High risk of Helicobacter pylori infection associated with cow's milk antibodies in young diabetics

Antibody titres (IgA and IgG) for Helicobacter pylori were assayed in 69 insulin-dependent diabetes mellitus patients (42 males, age 1-20 years) and 310 healthy controls (171 males, age 1-20 years). A positive antibody titre for Helicobacter pylori was found in 18/69 diabetic subjects compared to 17/310 controls (p < 0.001). There was no difference between Helicobacter pylori positive and negative diabetic subjects as regards age, sex, duration of diabetes, diabetic control, insulin dose and SDS for weight and height. Gastroduodenoscopy revealed presence of Helicobacter pylori and evidence of gastric inflammation in 7/8 symptomatic diabetic children. There was a significant association in the diabetic subjects between positivity for anti-cow's milk protein and anti-Helicobacter antibodies, compared to the control group. Seven of the 17 diabetics studied within 3 months of the onset of diabetes had positive antibody titres for Helicobacter. Of these seven patients, five were positive for anti-cow's milk protein antibodies. In our study the prevalence of Helicobacter pylori infection was significantly higher in diabetic subjects than in controls, but the infection was asymptomatic and there was no correlation with diabetes control. In diabetic subjects Helicobacter pylori infection was associated with a humoral response to cow's milk proteins and was often present from the onset of diabetes.

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.