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PubMed2000

Combined use of fasting plasma glucose and HbA1c predicts the progression to diabetes in Chinese subjects.

OBJECTIVE: We have previously suggested using the paired values of fasting plasma glucose (FPG) and HbA1c to identify potential diabetic subjects. In this article, we followed up on 208 nondiabetic subjects and examined their rates of progression to diabetes. We analyzed their likelihood of becoming diabetic according to their baseline FPG and HbA1c concentrations. RESEARCH DESIGN AND METHODS: Between 1988 and 1995, 2,877 Chinese subjects with risk factors for diabetes underwent screening. Of these, 2,250 had FPG <7.8 mmol/l and 2-h plasma glucose (PG) <11.1 mmol/l. Of these 2,250 subjects, 265 were randomly recruited for an annual oral glucose tolerance test (OGTT) until they progressed to develop diabetes. Of those 265 subjects, 57 had baseline FPG > or =7.0 mmol/l and were excluded from the present analysis. Hence, the progression of glucose tolerance in 208 subjects who were nondiabetic according to the new American Diabetes Association diagnostic criteria (FPG < 7.0 mmol/l and 2-h PG < 11.1 mmol/l) was examined RESULTS: Of the 208 nondiabetic subjects, 26 (12.5%) were men and 182 (87.5%) were women. After a mean follow-up of 1.60 +/- 1.16 years (range 1-7, median 1), 44 (21.2%) progressed to develop diabetes and 164 (78.8%) remained nondiabetic. Those who were diabetic at the end of the study had a high likelihood ratio (LR) of 9.3 to have baseline FPG > or =6.1 mmol/l and baseline HbA1c > or =6.1%. This was compared with a low LR of 0.6-1.1 in diabetic subjects who had either FPG <6.1 mmol/l or HbA1c <6.1% or both at baseline. The crude rate of progression to diabetes was more than five times higher (44.1 vs. 8.1%) in those whose baseline FPG was > or =6.1 mmol/l and baseline HbA1c was > or =6.1% compared with those whose baseline FPG was <6.1 mmol/l and baseline HbA1c was <6.1%. CONCLUSIONS: For Chinese subjects with risk factors for glucose intolerance, the use of paired FPG and HbA1c values helped to identify potential diabetic subjects. Those with an FPG > or =6.1 mmol/l and HbA1c > or =6.1% had a rate of progression to diabetes more than five times higher than those with an FPG <6.1 mmol/l and an HbA1c <6.1% after a mean follow-up of 1.6 years. Those with an FPG > or =6.1 but <7.0 mmol/l, especially if their HbA1c was > or =6.1%, should undergo an OGTT to confirm diabetes. Subjects with an FPG <6.1 mmol/l and/or an HbA1c <6.1% should have regular screening using the paired values of FPG and HbA1c.

Adult↗

PubMed2002

[Mapping of HbA1c as a quality measure in the primary care of diabetic patients in Thuringia, Germany].

BACKGROUND: In order to improve quality and outcome in the primary care for patients with diabetes mellitus it is necessary to recognise districts with poorer supply of structured diabetes care. Hba1c is an evaluated surrogate parameter which indicates the long-term control of diabetes therapy. The aim of the study was to create a map with all Hba1c-values of every district of the Free State of Thuringia, Germany. METHODS: Medical laboratories working for general practitioners were used as a new data source. All hba1c-values which were measured in Thuringia within the 4th quarter of 1997 were collected. A corresponding postal code was registered for each hba1c-value for identification purposes. Thuringia consists of 23 districts, and this geographic structure was used as a basis for the hba1c-map. RESULTS: 6 laboratories sent 23,214 hba1c-values. 16,591 values belonged to the territory of Thuringia: The medium relative hba1c (hba1c/mean normal of healthy people) for Thuringia was 1.44, two-fold increased hba1c was found in 7.9% of all hba1c values. The proportion of two-fold increased hba1c-values varied up to 100%. CONCLUSION: This pilot study disclosed significant differences in the outcome of regional ambulatory care for patients with diabetes mellitus in Thuringia. An intervention in districts with poorer study outcomes might result in direct benefits for patients and providers of health care services. Since hba1c-values could not be collected for all districts the first hba1c-map remains incomplete.

Biomarkers↗

PubMed2003

Standardization of two immunological HbA1c routine assays according to the new IFCC reference method.

The measurement of HbA1c is meanwhile well established as the most important parameter in clinical chemistry for monitoring the long term metabolic control of diabetic patients. However, the comparability of HbA1c values obtained by different methods in different laboratories and different countries is limited since there was no internationally agreed reference method available. Additionally the % HbA1c values, based on the most common DCCT values are too high due to well known non specificity of the DCCT standardization protocol. Recently a new reference method for the determination of HbA1c was developed and has been approved by the IFCC as the future basis for the worldwide standardization of HbA1c routine assays. The two routine methods from Roche Diagnostics (both based on the immunoturbidimetric determination of the stable glucose adduct to the N-terminal group of the hemoglobin beta chain, Roche-Hitachi/Tina-quant [a] and COBAS INTEGRA) are directly standardized against this new reference method. Both routine methods are based on a two step approach: in a first step the total Hb is quantified by a colorimetric method and in a second step the stable glucose adduct to the N-terminal group of the hemoglobin beta chain is quantified by immunoturbidity (HbA1c mass). Consequently, first the standardization of the total Hb assay was reconfirmed by method comparisons against the cyanomethemoglobin reference method. Second, the standardization of the HbA1c mass was done by running method comparisons against the new IFCC reference method. The resulting new calibrator values for HbA1c [mass] and total Hb [mass] allow a direct estimation of % HbA1c according to IFCC just by calculating the HbA1c [mass]/total Hb [mass] ratio. Good linear correlations were obtained when comparing the routine methods against the new IFCC reference, indicating the high specificity of these immunological approaches. The following correlations are obtained: Hitachi / Tina-quant [a] (Y) versus IFCC reference method (X): Y = -0.031 + 1.009 x X; r = 0.995. COBAS INTEGRA (Y) versus IFCC reference method (X): Y = -0.156 + 1.006 x X; r = 0.997. Hitachi / Tina-quant [a] (Y) versus Integra (X); (both standardized according to IFCC): Y = 0.057 + 1.003 x X; r = 0.997. The HbA1c values obtained with this new IFCC standardization are significantly lower than the well known DCCT values. Due to the specificity of the immunological approach which is very close to the analyte as defined by the IFCC reference method, no further corrections of the obtained % HbA1c values are necessary. A slope/intercept correction formula is derived which allows the transformation of IFCC values into the DCCT numbers if requested.

Blood Chemical Analysis↗

PubMed1999

Improvements in diabetic care as measured by HbA1c after a physician education project.

OBJECTIVE: To measure the quality of diabetic care as indicated by HbA1c testing frequency and HbA1c values and to demonstrate improvement in care after an appropriate quality improvement intervention. RESEARCH DESIGN AND METHODS: The quality improvement project used computerized claims and laboratory data relating to HbA1c testing among the private practices of nine physicians caring for diabetic Medicare patients. Nine indicators evaluated three main areas: HbA1c testing frequency, HbA1c values, and frequency of office visits. A quality improvement intervention consisting of a physician component and a patient component was implemented. RESULTS: There were 835 patients and 4,367 visits studied. After the intervention, statistically significant improvements in HbA1c testing frequency and values were noted. Rates of seized opportunities for testing HbA1c improved from 17.7 to 33.9% (P < 0.0001). The percentage of patients with a current HbA1c value improved from 31.3 to 47.6% (P < 0.0001). The median HbA1c values fell from 8.5 to 7.8% (P < 0.006). Patients achieving good or fair control (HbA1c < or = 8%) improved from 43.8 to 56.9% (P = 0.007). The median time between physician visits fell from 70 days to 60 days (P < 0.0001). CONCLUSIONS: The study revealed that HbA1c testing was underused but that after a quality improvement initiative, a significant increase in testing use could be achieved. The quality improvement initiative also resulted in significant improvements in glycemic control. The techniques and interventions used in this study could be used to intervene in larger populations and practice settings to improve medical care for diabetic patients.

Aged↗

PubMed2005

Adjunctive therapy with pramlintide lowers HbA1c without concomitant weight gain and increased risk of severe hypoglycemia in patients with type 1 diabetes approaching glycemic targets.

AIMS: In long-term clinical trials in patients with type 1 diabetes spanning a wide range of HbA1c, addition of pramlintide to existing insulin regimens led to reductions in HbA1c that were accompanied by weight loss and no increase in overall severe hypoglycemia event rates. Given that weight gain and increased hypoglycemia risk contribute to the difficulty of attaining HbA1c targets (<7 %), the question arose whether pramlintide could benefit patients approaching, but not reaching glycemic targets with insulin alone. To address this question, we conducted a pooled analysis from 3 long-term clinical trials, including all patients with an entry HbA1c between 7.0 % and 8.5 %. METHODS: Within the subset of patients with an entry HbA1c between 7.0 % and 8.5 % (approximately 28 % of all patients enrolled in the 3 studies), 196 were treated with placebo + insulin (baseline HbA1c 7.9+/-0.4 %, body weight 76.0+/-14.3 kg [mean+/-SD]) and 281 with pramlintide+insulin (baseline HbA1c 7.9+/-0.4 %, body weight 75.4+/-13.1 kg). Endpoints included placebo-corrected changes from baseline to week 26 in HbA1c, body weight, and the event rate of severe hypoglycemia. RESULTS: Adjunctive therapy with pramlintide resulted in significant reductions in HbA1c and body weight from baseline to week 26 (0.3 % and 1.8 kg, placebo-corrected treatment differences, respectively, both p<or=0.0009). These changes occurred without an increase in the overall risk of severe hypoglycemia (1.40 pramlintide vs. 1.86 placebo, events/patient-year of exposure). CONCLUSIONS: Addition of pramlintide to insulin therapy may help patients with type 1 diabetes who are approaching, but not yet reaching, glycemic targets with insulin alone to achieve further reductions in HbA1c without concomitant weight gain and increased risk of severe hypoglycemia.

Adult↗

PubMed2004

A different approach to analyzing age-related HbA1c values in non-diabetic subjects.

Using appropriate statistical tests and taking into account the analytical performance of hemoglobin A1c (HbA1c) measurements, is it useful to establish HbA1c age-related values in non-diabetic subjects? Non-diabetic subjects (n=135, 72 women and 63 men) from the neuromuscular department of the Pitié-Salpétrière Hospital (Paris) were involved in our study. Subjects were divided into two groups related to age: 51 patients under 50 years old and 84 subjects aged 50 years or more. Fasting plasma glucose and HbA1c measurements were respectively performed by enzymatic assay using the hexokinase method and high-performance liquid chromatography based on the ion exchange methodology with high precision. We first checked the normality of HbA1c distribution using the Kolmogorov-Smirnov test. Then we compared mean HbA1c in the two age subgroups using the Student's t test. Mean HbA1c was significantly (p<0.0001) higher in the subgroup aged 50 years or more (mean HbA1c=5.2%) than in younger subjects (mean HbA1c=5.0%). Then plots were drawn to check the relationship between HbA1c and age. Under the hypothesis of linearity, determination coefficients (R2) were calculated. However, considering their low values, this hypothesis must be rejected and other factors than age must be retained to explain HbA1c variability.

Adult↗

PubMed1995

Effect of aging on HbA1c in a working male Japanese population.

OBJECTIVE: To evaluate whether there is any change in HbA1c with age and to determine the effects of body mass index (BMI), exercise, and family history of diabetes on this change. RESEARCH DESIGN AND METHODS: A cross-sectional survey of 7,664 male Japanese workers aged 20-59 years was performed. All subjects received a physical examination that included measurement of HbA1c as an indicator of plasma glucose level. The subjects were classified according to their ages and BMIs, and any relationship with HbA1c levels was evaluated. Information on physical activity and family history of diabetes was obtained by a questionnaire. RESULTS: In all BMI groups, HbA1c increased with age. The greatest increase in HbA1c was observed in the 40- to 49-year-old age-group in subjects with a BMI < or = 26 kg/m2 and in the 30- to 39-year-old age-group in subjects with a BMI > 26. HbA1c in the subjects aged 20-29 years did not change with BMI. In contrast, HbA1c in subjects aged 30-59 years was significantly higher in those with a BMI > 26 when compared with those with BMI < or = 20. The age-dependent increase in HbA1c was greater in subjects with a positive rather than negative family history of diabetes. This age-dependent increase was not affected by active participation in sporting activities of mild to moderate intensity for 3 or more days per week. CONCLUSIONS: The age-dependent increase in HbA1c may be a consequence of the aging process itself. Furthermore, both BMI and a hereditary predisposition to diabetes, but not active participation in sports, affect this age-dependent increase in HbA1c.

Adult↗

PubMed1998

Comparison of percent total GHb with percent HbA1c in people with and without known diabetes.

OBJECTIVE: To directly compare results obtained using an ion-exchange high-performance liquid chromatography (HPLC) HbA1c method used in the Diabetes Control and Complications Trial with two different affinity chromatography methods in which "total GHb" is determined. RESEARCH DESIGN AND METHODS: Blood was obtained from a large number of people with and without known diabetes. The specimens were divided and assayed for HbA1c and for total GHb. Total GHb was determined using a semi-automated gravity-elution boronate affinity chromatography method and an automated boronate affinity HPLC method. The results obtained with the two methods were also compared. RESULTS: In subjects without known diabetes, the mean percentage HbA1c and the range of values were similar to the total GHb values in the same subjects when assayed using the semi-automated affinity gravity-elution method (mean 5.2 +/- 0.4 and 5.1 +/- 0.4% [SD], respectively). With the affinity HPLC method, results were 5.3 +/- 0.4%. The similarity in results was surprising. However, analysis of the data suggests that a large proportion of the material in the HbA1c fraction measured using this ion-exchange HPLC method is not GHb, as pointed out by others. Although the results were similar in people without known diabetes, in the people with diabetes, the incremental increase was approximately 25% greater for the total GHb when compared with the increase in HbA1c. When corrected for the non-GHb being measured by the HbA1c method, it can be calculated that approximately 40% more GHb is measured using affinity chromatography over the entire range of GHb values. CONCLUSIONS: The similarity in the mean and range of percent HbA1c and in percent total GHb using these different methods can be attributed to two factors: 1) the HbA1c ion-exchange method measures only approximately 50-60% of the total GHb present, and 2) approximately 40-50% of the material being measured in the HbA1c fraction is not GHb, i.e., offsetting factors fortuitously resulted in values similar to the more specific affinity methods. The greater incremental increase in percent total GHb compared with percent HbA1c in people with diabetes can be attributed to the greater amount of GHb being measured with the affinity methods.

Adolescent↗

PubMedDate not supplied

The relationship of postprandial glucose to HbA1c.

The gold standard for the assessment of the overall glycemic control is the determination of HbA1c. There are, however, insufficient data to determine reliably the relative contribution of fasting and postprandial plasma glucose to HbA1c. Increasing evidence suggests that excessive excursions of postprandial glucose might be important for the development of micro- and macroangiopathic complications. With respect to the treatment options, one important question to be answered is whether premeal, postmeal or fasting plasma glucose, alone or in combination, will be necessary in adjusting the therapy to achieve optimal HbA1c levels while minimizing hypoglycemia. HbA1c is difficult to predict from fasting plasma glucose. There are indications that there is a shift in the relative contribution from postprandial glucose at good to fair HbA1c levels (<7.3% to <9.2%) to fasting plasma glucose at high HbA1c (>9.3%). There is also a better correlation of afternoon and evening plasma glucose with HbA1c than with prebreakfast and prelunch plasma glucose values. Since the definition on how to define postprandial glucose is still a matter of debate and since postprandial glucose depends on the premeal blood glucose level and, on the time of the meal, its size and composition and the therapeutic strategy, the data so far available are inconclusive and the best correlation of HbA1c is with the area under the glucose profiles. Continuous glucose monitoring under daily life conditions will be the key to definitely unravel the relationship among HbA1c and fasting, premeal, postprandial and postabsorptive plasma glucose.

Blood Glucose↗

PubMed2005

Determination of HbA1c concentrations in patients with acute myocardial infarction: comparison of the DCA 2000 device with the HPLC method.

BACKGROUND: Recent studies suggest that HbA1c is an important predictor of the glycometabolic state of patients admitted for acute myocardial infarction (AMI). OBJECTIVE: We aimed at comparing the results of HbA1c concentrations obtained by 2 different methods in patients with AMI. RESEARCH DESIGN AND METHODS: In a first study, HbA1c was measured in all patients consecutively hospitalized for AMI, during a 6 month period using the HPLC method and the DCA 2000 device in the biochemistry laboratory. In a second study, HbA1c measured by the DCA 2000 device in the intensive care unit was compared with HbA1c determined by HPLC in the biochemistry laboratory in a similar sample of patients. In patients without personal history of diabetes, those patients with HbA1c > 6.5% (HPLC method), were classified as possible diabetes. RESULTS: A total of 146 patients were included (119 males, 27 females; mean age: 63 +/- 15 years). Twenty-seven of the patients had a personal history of diabetes. HbA1c determined by 2 techniques were highly correlated (r = 0.939, P < 0.0001). The mean of the differences (Bland and Altman analysis) was 0.4 +/- 0.3%. Compared with the HPLC method, the sensitivity of DCA 2000 device for the detection of possible diabetes was 81.8 +/- 11.6 and the specificity was 99.1 +/- 0.9%. The diagnostic accuracy of DCA method was 97.5 +/- 1.4%. In the second study, the HbA1c concentrations of 21 additional subjects, determined in an intensive care unit, were not different from the first 21 patients of the first study. CONCLUSIONS: HbA1c can be effectively determined using the DCA 2000 device. This method is reliable and easy to be implemented in an intensive care unit.

Autoanalysis↗

PubMed2005

Gestational diabetes: a reappraisal of HBA1c as a screening test.

BACKGROUND: Recent technological advances have made HBA1c a more standardized and user-friendly test with wide availability. This study evaluated HBA1c as a screening test for gestational diabetes mellitus (GDM) in a high-risk population. METHODS: A total of 442 pregnant women were assessed by HBA1c. Two thresholds were used to "rule in or rule out" GDM, which was confirmed by the "gold-standard" 75-g OGTT (World Health Organization criteria). RESULTS: Eighty-four (19%) women had GDM while 358 (81%) women were normal; there was a complete overlap of the HBA1c histograms of the two populations. The area under receiver operating characteristic curve of HBA1c to detect GDM was 0.54 (95% CI 0.48-0.61). Using a value of <5.5% to rule out GDM; a sensitivity of 82.1% was achieved, with 15 (16.7%) of 90 women below the threshold being false-negatives (NPV = 83.3%). Using a threshold of HBA1c > or = 7.5% to rule-in GDM; the specificity was 95.8% with 15 (71.4%) of 21 patients over the threshold being false-positives (PPV = 28.6%). HBA1c would eliminate the need for an OGTT in 25.1% (111/442) of whom 27% (30/111) women would be misclassified. At any HBA1c threshold with an acceptable sensitivity, the false-positive rate remained high making it necessary for too many healthy women to undergo the confirmatory OGTT. CONCLUSION: Despite all the progress in methodology, HBA1c remains a poor test to screen for GDM.

Adolescent↗

PubMed2006

The relationship of plasma glucose and HbA1c Levels among emergency department patients with no prior history of diabetes mellitus.

OBJECTIVES: Patients without a history of diabetes mellitus may be incidentally found to be hyperglycemic in the emergency department (ED). If the hyperglycemia is due to undiagnosed diabetes, then an opportunity for detection exists. Hemoglobin A1c (HbA1c) provides a weighted average of blood glucose levels over the past several months; high HbA1c levels could indicate diabetes. The objective of this study was to determine whether hyperglycemia in ED patients without a history of diabetes was associated with higher HbA1c levels. METHODS: This was a prospective nonconsecutive case series of adults aged 18 years or older presenting to the ED with acute illness for whom a plasma glucose sample was drawn for clinical management. A history of diabetes/hyperglycemia or current symptoms of diabetes excluded patients. HbA1c levels were analyzed for a glucose cutoff of 110 mg/dL; the data were further analyzed using additional glucose cutoffs. Based on the Third National Health and Nutrition Examination Survey outpatient screening data, an HbA1c level > or =6.2% was considered elevated (sensitivity of 63% and specificity of 97% for identifying diabetes). RESULTS: There were 541 patients enrolled; the glucose level correlated with the HbA1c level (r = 0.60, p < 0.001). Among the 331 patients with a glucose level > or =110 mg/dL, 22.4% had an elevated HbA(1c) level; among the 210 patients with a glucose level < 110 mg/dL, 7.6% had an elevated HbA1c level. There were few patients (n = 13) with a glucose level > or =200 mg/dL, but most (85%) had an elevated HbA1c level. Among the 140 patients with a mildly elevated glucose level (110-125 mg/dL), 16.4% had an elevated HbA(1c) level. CONCLUSIONS: Elevated HbA1c levels are found in ED patients with elevated random plasma glucose values. ED patients with hyperglycemia may warrant referral for diabetes testing.

Biomarkers↗

PubMed2006

Comparison of glycated albumin (GA) and glycated hemoglobin (HbA1c) in type 2 diabetic patients: usefulness of GA for evaluation of short-term changes in glycemic control.

We studied the cross-sectional relationship between GA and HbA1c in 142 type 2 diabetic patients who had an HbA1c level < 7.5% for at least one year without fluctuation by more than 0.5%. We also followed the changes of GA and HbA1c in 18 type 2 diabetic patients for 16 weeks as they progressed from untreated severe hyperglycemia (HbA1c > or = 9.0%) to good glycemic control (HbA1c < or = 6.5%) by intensive insulin treatment. The annual mean levels of GA and HbA1c in the stably controlled patients showed a weak, but significant, correlation (r = 0.23, p<0.001) in the 142 diabetic patients. However, the GA/HbA1c ratio ranged widely from 2.0 to 4.0 showing a normal distribution (2.9 +/- 0.34, M +/- SE), although patients with conditions affecting albumin turnover or RBC lifespan were excluded from the study. The GA/HbA1c ratio was significantly higher when patients were in hyperglycemic than when glycemic control was good (3.5 +/- 0.15 vs. 2.9 +/- 0.07, M +/- SE, p<0.01). GA decreased more rapidly than HbA1c during intensive insulin therapy, but the percent reduction of HbA1c eventually corresponded with that of GA by 16 weeks after the start of treatment. These results demonstrate that, although unknown influences on GA or HbA1c may exist, GA may be a useful marker for monitoring short-term variations of glycemic control during treatment of diabetic patients.

Aged↗

PubMed2000

Performance status of health care facilities changes with risk adjustment of HbA1c.

OBJECTIVE: To develop a risk adjustment method for HbA1c, based solely on administrative data and to determine the extent to which risk-adjusted HbA1c changes the identification of high- or low-performing medical facilities. RESEARCH DESIGN AND METHODS: Through use of pharmacy records, 204,472 diabetic patients were identified for federal fiscal year 1996 (FY96). Complete information (HbA1c levels, demographic data, inpatient records, outpatient pharmacy utilization records) was available on 38,173 predominantly male patients from 48 Veterans Health Administration (VHA) medical facilities. Hierarchical mixed-effects models were used to estimate risk-adjusted unique facility-level HbA1c. RESULTS: Predicted HbA1c demonstrated expected patterns for major factors known to influence glycemic control. Poorer glycemic control was seen in minorities and patients with greater disease severity, longer duration of disease (using treatment type or presence of amputation as surrogates), and more extensive comorbidity (measured by an adapted Charlson index). Better glycemic control was seen in Caucasians, older diabetic patients, and patients with higher outpatient utilization. The number of performance outliers was reduced as a result of risk adjustment. For mean HbA1c levels, 7 facilities that were initially identified as statistically significant outliers were no longer outliers after risk adjustment. For high-risk HbA1c (>9.5%) rates, 12 facilities that were initially identified as statistically significant outliers were no longer outliers after risk adjustment. CONCLUSIONS: Risk adjustment using only administrative data resulted in substantial changes in identification of high or low performers compared with non-risk-adjusted HbA1c. Although our findings are exploratory, risk adjustment using administrative data may be a necessary and achievable step in quality assessment of diabetes care measured by rates of high-risk HbA1c (>9.5%).

Adult↗

PubMed1999

Quality control, quality assessment of laboratory tests, HbA1c.

HbA1c level is known to be highly correlated with blood sugar level for a while after the maximum blood sugar level was observed, and is now considered more reliable than blood sugar as a long-term index of blood sugar control in diabetic patients. The Diabetes Control and Complication Trial in United States of America reported that mean HbA1c was the dominant predictor of retinopathy progression and that 10% lower HbA1c (e.g., 8 vs. 7.2 %) is associated with a 43 % to 45 % lower risk of progression of retinopathy. This report indicated that only a 1% difference in HbA1c level has a critical effect on progression of diabetic retinopathy. It also indicates the need for high precision and accuracy of hemoglobin A1c determination for control of diabetes patients. There are various methods to measure HbA1c. but now most laboratories use the high-performance liquid chromatography (HPLC) method; immunoassay is the second most popular, followed by affinity chromatography. It has been reported that each of these methods has its own characteristics, and that their results can vary considerably. In addition, there are two types of HbA1c, one a stable component and the other a labile component, and the measured HbA1c values were influenced by the contents of labile component included in the sample. The Japan Diabetes Society took a leading role and organized a committee on inter-laboratory standardization of HbA1c Determination in 1994. The HPLC method, which eliminates labile components, is used in most laboratories. Also, the number of laboratories using the immunoassay has gradually increased, while use of the other methods has rapidly decreased. In conclusion, since the proposal of a reference method and initiation of supply of reference materials by the Japan Diabetes Society, inter-laboratory differences in measured values have become much smaller, mainly due to the methods used for measurements. We need to continue efforts toward further standardization of HbA1c determination.

Blood Chemical Analysis↗

PubMed2002

A comparison of fructosamine and HbA1c for home self-monitoring blood glucose levels in type 2 diabetes.

BACKGROUND: Optimal glycemic control is believed to be essential in patients with diabetes to minimize any long-term complications. Measurement of the levels of glycated protein, such as fructosamine and glycated hemoglobin (HbA1c), is the most reliable method for assessing a period of glycemic control. This prospective study was performed to investigate whether fructosamine or HbA1c could provide a reliable index of glycemic control in type 2 diabetes. METHODS: Twenty-five patients with type 2 diabetes were studied at four-week intervals. Their fasting, preprandial and postprandial blood glucose levels were checked by glucometer twice a week for 16 weeks. Serum fructosamine and HbA1c were measured on every visit. The correlation of fructosamine and HbA1c with self-monitoring of blood glucose (SMBG) values in the previous 1 to 16 weeks prior to their measurements were calculated. RESULTS: Both fructosamine and HbA1c were significantly correlated with SMBG values from one week to 16 weeks prior to measurements. The correlation between fructosamine and SMBG was stronger in the prior 3 to 6 weeks. The correlation between HbA1c and SMBG was higher in the previous 4 to 12 weeks with the peak falling in the previous 8-10 weeks. Except for the previous one week, all the correlations were significantly stronger between HbA1c and SMBG than between fructosamine and SMBG. CONCLUSIONS: In type 2 diabetes, serum fructosamine assay can better reflect average blood glucose concentration over the previous 3 to 6 weeks and HbA1c is better reflective over the previous 8 to 10 weeks. HbA1c measurement correlates more significantly with home capillary blood glucose levels than the fructosamine assay, even over the previous 2 to 3 weeks.

Adult↗

PubMed1995

The relationship of glycemic exposure (HbA1c) to the risk of development and progression of retinopathy in the diabetes control and complications trial.

The Diabetes Control and Complications Trial (DCCT) demonstrated that a regimen of intensive therapy aimed at maintaining near-normal blood glucose values markedly reduces the risks of development or progression of retinopathy and other complications of insulin-dependent diabetes mellitus (IDDM) when compared with a conventional treatment regimen. This report presents an epidemiological assessment of the association between levels of glycemic exposure (HbA1c) before and during the DCCT with the risk of retinopathy progression within each treatment group. The initial level of HbA1c observed at eligibility screening as an index of pre-DCCT glycemia and the duration of IDDM on entry were the dominant baseline predictors of the risk of progression. The shorter the duration of IDDM on entry, the greater were the benefits of intensive therapy. In each treatment group, the mean HbA1c during the trial was the dominant predictor of retinopathy progression, and the risk gradients were similar in the two groups; a 10% lower HbA1c (e.g., 8 vs. 7.2%) is associated with a 43% lower risk in the intensive group and a 45% lower risk in the conventional group. These risk gradients applied over the observed range of HbA1c values and were unaffected by adjustment for other covariates. Over the range of HbA1c achieved by DCCT intensive therapy, there does not appear to be a level of glycemia below which the risks of retinopathy progression are eliminated. The change in risk over time, however, differed significantly between the treatment groups, the risk increasing with time in the study in the conventional group but remaining relatively constant in the intensive group. The risks were compounded by a multiplicative effect of the level of HbA1c with the duration of exposure (time in study). Total glycemic exposure was the dominant factor associated with the risk of retinopathy progression. When examined simultaneously within each treatment group, each of the components of pre-DCCT glycemic exposure (screening HbA1c value and IDDM duration) and glycemic exposure during the DCCT (mean HbA1c, time in study, and their interaction) were significantly associated with risk of retinopathy progression. Similar results also apply to other retinopathic, nephropathic, and neuropathic outcomes. The recommendation of the DCCT remains that intensive therapy with the goal of achieving near-normal glycemia should be implemented as early as possible in as many IDDM patients as is safely possible.

Biomarkers↗

PubMed1996

Long-term intensive insulin therapy in IDDM: effects on HbA1c, risk for severe and mild hypoglycaemia, status of counterregulation and awareness of hypoglycaemia.

UNLABELLED: The present studies were designed to assess the percentage of HbA1c, frequency, and awareness of hypoglycaemia (H) during long-term intensive therapy (IT) of insulin-dependent diabetes mellitus (IDDM). From 1981 to 1994, 112 IDDM patients were on IT. HbA1c was 7.17 +/- 0.16% (non-diabetic subjects 3.8-5.5%), the frequency of severe H 0.01 +/- 0.009 episodes/patient-year, frequency of mild symptomatic H 35.6 +/- 2.9 episodes/patient-year. IDDM patients with HbA1c < or = 5.5% (Group I, n = 10), between 6.1-7.0% (Group II, n = 12), and > or = 7.6% (Group III, n = 11) were studied to assess responses of counterregulatory hormones, symptoms and cognitive function during experimental, stepped H. Compared to 18 non-diabetic subjects, Group I exhibited high thresholds (plasma glucose had to decrease more than normal to evoke responses), and impaired responses of adrenaline, unawareness of H and delayed onset of cognitive dysfunction at the lowest glycaemic plateau (2.3 mmol/l). Group II had normal thresholds and responses, whereas Group III had low thresholds. Frequency of mild H was higher in Group I (54.5 +/- 1.9 episodes/patient-year) than in Group II and III (33.7 +/- 3.5 and 20.4 +/- 2.5 episodes/patient-year, respectively, p < 0.001) and correlated with percentage of HbA1c (r = -0.82). IN CONCLUSION: IT can maintain near-normal HbA1c and is compatible with low frequency of severe H. However, if HbA1c is less than 6.0%, mild, symptomatic H is excessively frequent and causes impaired counterregulation and H unawareness. Efforts should be made not only to maintain HbA1c < or = 7.0%, but also to prevent, recognize and reverse iatrogenic H unawareness during long-term IT of IDDM by maintaining HbA1c > 6.0%.

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