Frequency of HbA1c discordance in estimating blood glucose control

Evaluating HbA1c-to-average glucose conversion with patient-specific kinetic models for diverse populations

The discrepancy between estimated glycemia from HbA1c values and actual average glucose (AG) levels has significant implications for treatment decisions and patient understanding. Factors contributing to the gap include red blood cell (RBC) lifespan and glucose uptake into the RBC. Personalized models have been proposed to enhance AG prediction accuracy by considering interpersonal variation. This study contributes to our understanding of personalized models for estimating AG from HbA1c. Utilizing data from seven studies (340 participants), including Hispanic/Latino populations with or at risk of non-insulin-treated type 2 diabetes (T2D), we examined kinetic features across cohorts. Additionally, the study simulated scenarios to understand data requirements for improving accuracy. Personalized approaches improved agreement between AG estimations and CGM-AG, particularly with four or more weeks of training CGM data. A multiple linear regression model using kinetic parameters and added clinical features was shown to improve the accuracy of personalized models further. As CGM usage extends beyond type 1 diabetes, there is growing interest in leveraging CGM data for clinical decision-making. Patient-specific models offer a valuable tool for managing glycemic status in patients with discordant HbA1c and AG values.

Effect of a Disease Management Program on the Adherence to Guideline-Recommended HbA1c Monitoring in Patients with Diabetes in Slovakia

INTRODUCTION

Glycated hemoglobin (HbA1c) is a crucial marker of glucose control that is widely utilized in the management of diabetes mellitus. The aim of this study was to evaluate the effect of a diabetes management program (DMP) offered by a health insurance company, together with the effects of other factors associated with patient and physician characteristics, on the frequency of HbA1c testing in outpatient diabetes clinics in Slovakia.

METHODS

A retrospective analysis was conducted to compare the frequency of HbA1c measurements in patients under the care of physicians participating in the DMP with those who did not, spanning the years 2015 to 2019. In 2019, a total of 74,384 patients with diabetes were included in the analysis, of which 52% were men and 48% were women, with an average age of 64.1 years.

RESULTS

At the end of the study period, the average annual number of HbA1c measurements was significantly higher in patients treated by physicians participating in the DMP than in patients treated by physicians who were not (2.50 vs. 1.91 per year, respectively; P < 0.001). There was a substantial increase in HbA1c testing at least twice yearly in both groups, but the growth rate was greater in the group with DMP-engaged diabetologists (14.3%) compared to the diabetes specialists who were not involved in the DMP (5.1%). In the multivariate analysis, participation in the DMP was correlated with an increase in HbA1c tests per year by 0.7.

CONCLUSIONS

Physician participation in a DMP was found to significantly increase the number of HbA1c tests ordered by physicians, potentially leading to improved glycemic control.

Association of cardio-renal biomarkers and mortality in the U.S.: a prospective cohort study

OBJECTIVE

Diabetes poses a significant threat to human health. There is a lack of large-scale cohort studies to explore the association between mortality risk and indicators beyond blood glucose monitoring in diabetic populations.

METHODS

Multivariable Cox proportional hazards regression models were performed to investigate the association of 13 blood biomarkers with mortality risk in the National Health and Nutrition Examination Survey (NHANES) and biomarker levels were log-transformed and correlated with mortality.

RESULTS

During a median follow-up of 7.42 years, 1783 diabetic patients were enrolled. Compared to traditional risk factors, the addition of hs-cTnT, hs-cTnI, NT-proBNP, creatinine, cystatin C, and β-2 microglobulin biomarkers increased the predictive ability for all-cause mortality by 56.4%, 29.5%, 38.1%, 18.8%, 35.7%, and 41.3%, respectively. However, the inclusion of blood glucose monitoring had no impact on the prediction of all-cause mortality. Compared with the 1st quartiles of creatinine and Cystatin C, the risk of diabetes mortality were higher in the highest quartiles (HR: 5.16, 95% CI: 1.87-14.22; HR: 10.06, 95% CI: 4.20-24.13).

CONCLUSIONS

In the diabetic population, elevated plasma levels of hs-cTnT, hs-cTnI, NT-proBNP, creatinine, cystatin C, and β-2 microglobulin serve as robust and straightforward predictors of long-term mortality compared to blood glucose levels and HbA1c values. Creatinine and cystatin C stand out as more precise markers for predicting diabetes mortality prior to blood glucose monitoring.

CGMap: Characterizing continuous glucose monitor data in thousands of non-diabetic individuals

Despite its rising prevalence, diabetes diagnosis still relies on measures from blood tests. Technological advances in continuous glucose monitoring (CGM) devices introduce a potential tool to expand our understanding of glucose control and variability in people with and without diabetes. Yet CGM data have not been characterized in large-scale healthy cohorts, creating a lack of reference for CGM data research. Here we present CGMap, a characterization of CGM data collected from over 7,000 non-diabetic individuals, aged 40-70 years, between 2019 and 2022. We provide reference values of key CGM-derived clinical measures that can serve as a tool for future CGM research. We further explored the relationship between CGM-derived measures and diabetes-related clinical parameters, uncovering several significant relationships, including associations of mean blood glucose with measures from fundus imaging and sleep monitoring. These findings offer novel research directions for understanding the influence of glucose levels on various aspects of human health.

Continuous glucose monitoring metrics (Mean Glucose, time above range and time in range) are superior to glycated haemoglobin for assessment of therapeutic efficacy

AIM

To evaluate continuous glucose monitoring (CGM) metrics for use as alternatives to glycated haemoglobin (HbA1c) to evaluate therapeutic efficacy.

METHODS

We re-analysed correlations among CGM metrics from studies involving 545 people with type 1 diabetes (T1D), 5910 people with type 2 diabetes (T2D) and 98 people with T1D during pregnancy and the postpartum period.

RESULTS

Three CGM metrics, interstitial fluid Mean Glucose level, proportion of time above range (%TAR) and proportion of time in range (%TIR), were correlated with HbA1c and provided metrics that can be used to evaluate therapeutic efficacy. Mean Glucose showed the highest correlation with %TAR (r = 0.98 in T1D, 0.97 in T2D) but weaker correlations with %TIR (r = -0.92 in T1D, -0.83 in T2D) or with HbA1c (r = 0.78 in T1D). %TAR and %TIR were highly correlated (r = -0.96 in T1D, -0.91 in T2D). After 6 months of use of real-time CGM by people with T1D, changes in Mean Glucose level were more highly correlated with changes in %TAR (r = 0.95) than with changes in %TIR (r = -0.85) or with changes in HbA1c level (r = 0.52). These metrics can be combined with metrics of hypoglycaemia and/or glycaemic variability to provide a more comprehensive assessment of overall quality of glycaemic control.

CONCLUSION

The CGM metrics %TAR and %TIR show much higher correlations with Mean Glucose than with HbA1c and provide sensitive indicators of efficacy. Mean glucose may be the best metric and shows consistently higher correlations with %TAR than with %TIR.

Hemoglobin A1c, hemoglobin glycation index, and triglyceride and glucose index: Useful tools to predict low feed intake associated with glucose intolerance in lactating sows

The aim of the present study was to evaluated hemoglobin A1c (HbA1c), the hemoglobin glycation index (HGI), and triglyceride and glucose (TG) index as predictive indicators for low feed intake in lactating sows due to glucose intolerance. Cactus (Opuntia ficus-indica) was included in sow diets as a modulating factor of glucose. Thirty-six sows were separated into three groups (Gs). Although the three groups received a conventional diet during gestation and lactation, 2.0 kg per sow per day of steam-cooked cactus (G1) and fresh cactus (G2) were added to the lactation diet as a glycemic modulating factor, with G3 serving as the control group. Glycemia was assessed via glucometer (blood glucose concentrations), HbA1c and HGI. For each indicator of glycemia the triglycerides and glucose (TG) index was evaluated. The highest blood glucose concentration was observed on day 3 of lactation (88.2 mg/dL). The average glycemic concentrations obtained from HbA1c on farrowing day (61.6 mg/dL) and day 21 of lactation (65.6 mg/dL) were lower (p<0.05) than those measured by a glucometer on the same days (71.8 and 77.7 mg/dL for farrowing day and day 21 of lactation, respectively). At farrowing, the TG index obtained from the HGI indicated that 83.0% of sows were glucose intolerant, compared to 100% according to the TG index obtained from a glucometer. At weaning, 50% of G2 did not show glucose intolerance when the TG index was calculated using the HGI, compared to 54% when it was calculated with blood glucose concentrations measured by a glucometer. All G3 sows presented glucose intolerance, regardless of the test used. The HbA1c, HGI, and TG index tests are viable alternatives to predict low feed intake due to glucose intolerance in lactating sows.

Association of hemoglobin glycation index and its interaction with obesity/family history of hypertension on hypertension risk: a community-based cross-sectional survey

Background

Hemoglobin glycation index (HGI) is considered to be a convenient measurable indicator to assess the inter-individual variation of HbA1c. In the present study, we tested the relationship between HGI and risk of hypertension, and further explored the possible interacting influences of HGI with other such factors on hypertension risk among Chinese individuals.

Methods

The eligible subjects were chosen from a community-based cross-sectional survey in China. We collected relevant data and clinical indicators for each participant. HGI was calculated as “measured HbA1c-predicted HbA1c” and divided into four categories according to quartile. The following indicators were used to assess interactive effects: (1) relative excess risk due to interaction (RERI); (2) attributable proportion due to interaction (AP); and (3) synergy index (SI). Statistical analysis was performed using R software.

Results

Specifically, 1777 eligible participants were selected in this cross-sectional survey. There were 433 subjects who were identified to have hypertension (24.4%). A significant increase in the prevalence of hypertension from Q1 to Q4 of HGI was observed (p < 0.001). Multivariable logistic model demonstrated that subjects at the highest HGI group had a substantially increased risk of being hypertensive than subjects in the first quartile of HGI, as indicated by the OR value of 1.87 (95% CI 1.26–2.78). Moreover, a significant interaction between family history of hypertension and HGI on hypertension risk was detected (RERI: 1.36, 95% CI 0.11–2.63; AP: 0.43, 95% CI 0.17–0.69; and SI:2.68, 95% CI 1.10–6.48). The interactive effect between HGI and abdominal obesity was also found to be significant, as estimated by the value of RERI (1.04, 95% CI 0.24–1.85), AP (0.33, 95% CI 0.11–0.56) and SI (1.96, 95% CI 1.01–3.79). However, in the analysis of the interaction between HGI and general obesity, only the AP value (0.28, 95% CI 0.01–0.54) was observed to be significant.

Conclusion

High HGI was independently associated with the risk of hypertension. Moreover, HGI significantly shared interactions with obesity and family history of hypertension that influenced the risk of hypertension.

Implications of the Hemoglobin Glycation Index on the Diagnosis of Prediabetes and Diabetes

OBJECTIVE

Fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG) from a 75-g oral glucose tolerance test (OGTT) and glycated hemoglobin (HbA1c) can lead to different results when diagnosing prediabetes and diabetes. The Hemoglobin Glycation Index (HGI) quantifies the interindividual variation in glycation resulting in discrepancies between FPG and HbA1c. We used data from the Vitamin D and Type 2 Diabetes (D2d) study to calculate HGI, to identify HGI-associated variables, and to determine how HGI affects prediabetes and diabetes diagnosis.

MEASUREMENTS

A linear regression equation [HbA1c (%) = 0.0164 × FPG (mg/dL) + 4.2] was derived using the screening cohort (n = 6829) and applied to calculate predicted HbA1c. This was subtracted from the observed HbA1c to determine HGI in the baseline cohort with 2hPG data (n = 3945). Baseline variables plus prediabetes and diabetes diagnosis by FPG, HbA1c, and 2hPG were compared among low, moderate, and high HGI subgroups.

RESULTS

The proportion of women and Black/African American individuals increased from low to high HGI subgroups. Mean FPG decreased and mean HbA1c increased from low to high HGI subgroups, consistent with the HGI calculation; however, mean 2hPG was not significantly different among HGI subgroups.

CONCLUSIONS

High HGI was associated with Black race and female sex as reported previously. The observation that 2hPG was not different across HGI subgroups suggests that variation in postprandial glucose is not a significant source of population variation in HGI. Exclusive use of HbA1c for diagnosis will classify more Black individuals and women as having prediabetes compared with using FPG or 2hPG.

Effect of Prestroke Glycemic Variability Estimated Glycated Albumin on Stroke Severity and Infarct Volume in Diabetic Patients Presenting With Acute Ischemic Stroke

Background: We investigated whether prestroke glycemic variability, represented by glycated albumin (GA), affects the initial stroke severity and infarct volume in diabetic patients presenting with acute ischemic stroke. Methods: We evaluated a total of 296 acute ischemic stroke patients with diabetes mellitus who were hospitalized within 48 h of stroke onset. GA was measured in all acute ischemic stroke patients consecutively during the study period. The primary outcome was the initial National Institute Health Stroke Scale (NIHSS) score. The secondary outcome was infarct volume on diffusion-weighted imaging, which was performed within 24 h of stroke onset. Higher GA (≥16.0%) was determined to reflect glycemic fluctuation prior to ischemic stroke. Results: The number of patients with higher GA was 217 (73.3%). The prevalence of a severe initial NIHSS score (>14) was higher in patients with higher GA than in those with lower GA (3.8% vs. 15.7%, p = 0.01). The proportion of participants in the highest quartile of infarct volume was higher in the higher GA group (11.4% vs. 36.4%, p < 0.001). A multivariable analysis showed that higher GA was significantly associated with a severe NIHSS score (odds ratio, [95% confidence interval], 7.99 [1.75-36.45]) and large infarct volume (3.76 [1.05-13.45]). Conclusions: Prestroke glucose variability estimated by GA was associated with an increased risk of severe initial stroke severity and large infarct volume in acute ischemic stroke patients with diabetes mellitus.

Glycated haemoglobin (HbA1c ) and fasting plasma glucose relationships in sea-level and high-altitude settings

AIM

Higher haemoglobin levels and differences in glucose metabolism have been reported among high-altitude residents, which may influence the diagnostic performance of HbA_1c . This study explores the relationship between HbA_1c and fasting plasma glucose (FPG) in populations living at sea level and at an altitude of > 3000 m.

METHODS

Data from 3613 Peruvian adults without a known diagnosis of diabetes from sea-level and high-altitude settings were evaluated. Linear, quadratic and cubic regression models were performed adjusting for potential confounders. Receiver operating characteristic (ROC) curves were constructed and concordance between HbA_1c and FPG was assessed using a Kappa index.

RESULTS

At sea level and high altitude, means were 13.5 and 16.7 g/dl (P > 0.05) for haemoglobin level; 41 and 40 mmol/mol (5.9% and 5.8%; P < 0.01) for HbA_1c ; and 5.8 and 5.1 mmol/l (105 and 91.3 mg/dl; P < 0.001) for FPG, respectively. The adjusted relationship between HbA_1c and FPG was quadratic at sea level and linear at high altitude. Adjusted models showed that, to predict an HbA_1c value of 48 mmol/mol (6.5%), the corresponding mean FPG values at sea level and high altitude were 6.6 and 14.8 mmol/l (120 and 266 mg/dl), respectively. An HbA_1c cut-off of 48 mmol/mol (6.5%) had a sensitivity for high FPG of 87.3% (95% confidence interval (95% CI) 76.5 to 94.4) at sea level and 40.9% (95% CI 20.7 to 63.6) at high altitude.

CONCLUSION

The relationship between HbA_1c and FPG is less clear at high altitude than at sea level. Caution is warranted when using HbA_1c to diagnose diabetes mellitus in this setting.

Possible role of fructosamine 3-kinase genotyping for the management of diabetic patients

Diabetes mellitus is a global pandemic and continues to increase in numbers and significance. Several pathogenic processes are involved in the development of such disease and these mechanisms could be influenced by genetic, epigenetic and environmental factors. Non-enzymatic glycation reactions of proteins have been strongly related to pathogenesis of chronic diabetic complications. The identification of fructosamine 3-kinase (FN3K), an enzyme involved in protein deglycation, a new form of protein repair, is of great interest. FN3K phosphorylates fructosamines on the third carbon of their sugar moiety, making them unstable and causing them to detach from proteins, suggesting a protective role of this enzyme. Moreover, the variability in FN3K activity has been associated with some polymorphisms in the FN3K gene. Here we argue about genetic studies and evidence of FN3K involvement in diabetes, together with results of our analysis of the FN3K gene on a Caucasian cohort of diabetic patients. Present knowledge suggests that FN3K could act in concert with other molecular mechanisms and may impact on gene expression and activity of other enzymes involved in deglycation process.

Implications of using HBA1C as a diagnostic marker for diabetes

Diagnosing diabetes now includes a new criterion; hemoglobin A1_C ≥6.5 % which can have significant implications. This review compares the advantages and disadvantages of using HbA1_C as the main diabetic diagnostic test. HbA1_C has greater stability and less variability than plasma glucose measurements but may not always reflect glycemic levels of glycaemia. The present cut off value identifies fewer diabetics than glucose-based criteria. HbA1_C being more convenient could diagnose more patients but this is not yet proven. When choosing a diagnostic test, the limitations of each test must be clearly understood to use appropriate clinical judgment and consider patient preference.

Neutralizing Anti-IL20 Antibody Treatment Significantly Modulates Low Grade Inflammation without Affecting HbA1c in Type 2 Diabetic db/db Mice

Low grade inflammation is present in pre-clinical and human type 2 diabetes. In this process, several cytokines like IL-1β and inflammatory cells like macrophages are activated and demonstrated to participate to the disease initiation and progression. IL-20 is a cytokine known to play non-redundant roles in progression of several inflammatory diseases. To address the therapeutic effect of inhibiting the IL-20 pathway in diabetes, diabetic db/db mice were treated with neutralizing anti-IL20 antibodies in vivo and both metabolic and inflammatory parameters were followed. Diabetic islets expressed the IL-20 cytokine and all IL-20 receptor components in elevated levels compared to resting non-diabetic islets. Islets were responsive to ex vivo IL-20 stimulation measured as SOCS induction and KC and IL-6 production. Neutralizing anti-IL20 treatment in vivo had no effect on HbA1c or weight although the slope of blood glucose increase was lowered. In contrast, anti-IL20 treatment significantly reduced the systemic low-grade inflammation and modulated the local pancreatic immunity. Significant reduction of the systemic IL-1β and MCP-1 was demonstrated upon anti-IL20 treatment which was orchestrated with a reduced RANTES, IL-16 and IL-2 but increased TIMP-1, MCP-1 and IL-6 protein expression locally in the pancreas. Interestingly, anti-IL20 treatment induced an expansion of the myeloid suppressor CD11bGr1int macrophage while reducing the number of CD8 T cells. Taken together, anti-IL20 treatment showed moderate effects on metabolic parameters, but significantly altered the low grade local and systemic inflammation. Hence, future combination therapies with anti-IL20 may provide beneficial therapeutic effects in type 2 diabetes through a reduction of inflammation.

Extreme Levels of HbA1c Increase Incident ESRD Risk in Chinese Patients with Type 2 Diabetes: Competing Risk Analysis in National Cohort of Taiwan Diabetes Study

Background

Whether HbA1c is a predictor of end-stage renal disease (ESRD) in type 2 diabetes patients remains unclear. This study evaluated relationship between HbA1c and ESRD in Chinese patients with type 2 diabetes.

Methods

Patients aged ≥ 30 years who were free of ESRD (n = 51 681) were included from National Diabetes Care Management Program from 2002–2003. Extended Cox proportional hazard model with competing risk of death served to evaluate association between HbA1c level and ESRD.

Results

A total of 2613 (5.06%) people developed ESRD during a follow-up period of 8.1 years. Overall incidence rate of ESRD was 6.26 per 1000 person-years. Patients with high levels of HbA1c had a high incidence rate of ESRD, from 4.29 for HbA1c of  6.0%–6.9% to 10.33 for HbA1c ≥ 10.0% per 1000 person-years. Patients with HbA1c < 6.0% particularly had a slightly higher ESRD incidence (4.34 per 1000 person-years) than those with HbA1c  of 6.0%–6.9%. A J-shaped relationship between HbA1c level and ESRD risk was observed. After adjustment, patients with HbA1c < 6.0% and ≥ 10.0% exhibited an increased risk of ESRD (HR: 1.99, 95% CI: 1.62–2.44; HR: 4.42, 95% CI: 3.80–5.14, respectively) compared with those with HbA1c of 6.0%–6.9%.

Conclusions

Diabetes care has focused on preventing hyperglycemia, but not hypoglycemia. Our study revealed that HbA1c level ≥ 7.0% was linked with increased ESRD risk in type 2 diabetes patients, and that HbA1c < 6.0% also had the potential to increase ESRD risk. Our study provides epidemiological evidence that appropriate glycemic control is essential for diabetes care to meet HbA1c targets and improve outcomes without increasing the risk to this population. Clinicians need to pay attention to HbA1c results on diabetic nephropathy.

Glycemic control according to glomerular filtration rate in patients with type 2 diabetes and overt nephropathy: a prospective observational study

BACKGROUND AND OBJECTIVE

Type 2 diabetes (T2D) and chronic kidney disease (CKD) are closely linked. This study aimed to describe and analyze the relations between renal function and glycemic control in T2D patients with overt nephropathy.

PATIENTS AND METHODS

Data were collected from a French observational prospective multicenter study. Patients included were adults with T2D, clinical proteinuria and an estimated glomerular filtration rate (eGFR) over 15 mL/min/1.73 m(2). Baseline data and glycemic control after a one-year follow-up are presented here.

RESULTS

Data from 986 adult patients were analyzed. Mean age was 70 years. Mean eGFR was 42 mL/min/1.73 m(2), 66% of patients had proteinuria above 1g/day. HbA1c was higher in patients with lower eGFR in a model adjusted to age, gender, body mass index, hemoglobin level and erythropoietin use. Statistical significance was lost when stepwise multivariate analysis took into account the type of pharmacological treatment used to treat hyperglycemia.The type of antidiabetic agents differed across eGFR strata. Below 60 mL/min/1.73 m(2), the use of metformin declined while the use of insulin increased.After one year of follow up, 35% of patients had persistently poor or worsened glycemic control (HbA1c>8%). The only covariate independently associated with this characteristic was the duration of insulin therapy.

CONCLUSION

In patients with T2D and overt nephropathy, the observed correlation of low eGFR with high HbA1c was not predicted by eGFR. Our data rather underscore a different use of antidiabetic treatments in patients with advanced renal dysfunction, and the difficulty to improve glycemic control in patients with long standing insulin therapy.

Interpretation of HbA1c : association with mean cell volume and haemoglobin concentration

AIM

The utility of HbA1c in diabetes diagnosis is reduced in settings associated with altered haemoglobin glycation. We have studied whether HbA1c varies with mean cell volume and mean cell haemoglobin concentration as measures of haemoglobin metabolism.

METHODS

Randomly selected adults from rural Victoria, Australia, were invited for biomedical assessment. After excluding patients with known diabetes and/or serum creatinine ≥ 0.12 mmol/l, 1315 adults were included. Demography, arthropometric measurements, oral glucose tolerance test, analyses of full blood count and HbA1c were undertaken.

RESULTS

After adjusting for age, sex, ethnicity, BMI, town and socio-economic status, there were no significant differences in haemoglobin, mean cell volume or mean cell haemoglobin concentration by glycaemic status (defined by oral glucose tolerance test). HbA1c was significantly and independently associated with fasting glucose, town, mean cell haemoglobin concentration, ethnicity, age and BMI among men < 50 years (R² = 33.8%); fasting glucose, 2-h glucose, mean cell haemoglobin concentration and town among men ≥ 50 years (R² = 47.9%); fasting glucose, mean cell volume, mean cell haemoglobin concentration, town, 2-h glucose and age among women < 50 years (R² = 46.3%); fasting glucose, mean cell haemoglobin concentration, mean cell volume and 2-h glucose among women ≥ 50 years (R² = 51.6%). A generalized linear model showed a gradient from an adjusted mean HbA1c of 36 (95% CI 34-38) mmol/mol with a mean cell haemoglobin concentration of ≤ 320 g/l to 30 (95% CI 29-31) mmol/mol with a mean cell haemoglobin concentration of > 370 g/l. The gradient across mean cell volume was negative, but only by 1 mmol/mol (0.1%) HbA1c .

CONCLUSION

A mean HbA1c difference of 5 mmol/mol (0.5%) across the mean cell haemoglobin concentration reference range suggests that an accompanying full blood count examination may be required for its use in the diagnosis of diabetes. Further studies are required to confirm this.

In-depth comparative characterization of hemoglobin glycation in normal and diabetic bloods by LC-MSMS

The glycation level at β-Val-1 of the hemoglobin β chain in human blood (HbA1c%) is used to diagnose diabetes and other diseases. However, hemoglobin glycation occurs on multiple sites on different isoforms with different kinetics, but its differential profile has not been clearly demonstrated. In this study, hemoglobin was extracted from the blood of normal and diabetic individuals by protein precipitation. Triplicate solutions prepared from each sample were directly analyzed or digested with multiple enzymes and then analyzed by nano-LC/MS via bottom-up approach for side-by-side characterization. Intact hemoglobin analysis indicated a single glucose-dominant glycation, which showed good correlation with the HbA1c% values. Moreover, full sequence (100%) of α/β globin was mapped and seven glycation sites were unambiguously assigned. In addition to β-Val-1, two other major sites at α-Lys-61 and β-Lys-66, which contain the common sequence HGKK, and four minor sites (<1%) on α-Val-1, β-Lys-132, α-Lys-127, and α-Lys-40 were identified. All sites were shown to exhibit similar patterns of site distribution despite different glucose levels. Both the intact mass measurement and bottom-up data consistently indicated that the total glycation percentage of the β-globin was twice higher than the α-globin. Using molecular modeling, the 3D structure of the consensus sequence (HGKK) was shown to contain a phosphate triangle cavity, which helps to catalyze the glycation reaction. For the first time, hemoglobin glycation in normal and diabetic bloods was comparatively characterized in-depth with 100% sequence coverage. The results provide insight about the HbA1c parameter and help define the new and old markers.

Risk factors of retinopathy in type 2 diabetes mellitus at a tertiary care hospital, Bahawalpur Pakistan

Objectives: To find out the risk factors of diabetic retinopathy in type 2 diabetes mellitus.

Methodology: It was a cross-sectional study involving 300 patients of type 2 diabetes. Clinical history, relevant examination including fundoscopy and lab investigations were done. Data was analysed with SPSS 17.0. T-test and chi square/Fischer exact were applied to determine significance.

Results: Mean age of the patients was 49.04 ± 0.69 years with slight female predominance with male to female ratio of 3:4. Average duration of disease was 7.17 ± 0.38 years. Diabetic retinopathy was diagnosed in (74, 23.9%). Mean HbA1c was 8.15% in patients with retinopathy and 8.884% in those who had no retinopathy (p=0.08). However, duration of DM, age of patients, male gender, high total cholesterol, high LDL and microalbuminuria were significantly associated with the development of retinopathy.

Conclusions: Diabetic retinopathy was found in 23.9% of type 2 diabetics. It was associated with duration of disease, age at presentation, male gender, high total cholesterol, high LDL and microalbuminuria. A single high level of HbA1c was not associated with retinopathy.

Association of glycated albumin with the presence of carotid plaque in patients with type 2 diabetes

AIMS/INTRODUCTION

Postprandial hyperglycemia is a potent risk factor for cardiovascular disease. Serum glycated albumin (GA) has been reported to reflect postprandial blood glucose fluctuations. In the present study, we assessed the possible correlation of GA with the presence of carotid plaque to evaluate the potential clinical usefulness of GA for predicting atherosclerotic cardiovascular complications in patients with type 2 diabetes.

MATERIALS AND METHODS

Patients with type 2 diabetes (n = 236) admitted to Nippon Medical School Hospital (Tokyo, Japan) for glycemic control (aged 19-86 years, 81 females and 155 males) were examined. Clinical measurements were taken on admission. The presence of carotid plaque was assessed by ultrasonography.

RESULTS

In patients with carotid plaque (n = 154), GA (P = 0.023) was higher than those without carotid plaque (n = 82). In contrast, neither fasting plasma glucose (P = 0.48) nor glycated hemoglobin (P = 0.41) was significantly different between the groups. The results of logistic regression analysis showed that GA (age- and sex-adjusted odds ratio [95% confidence interval], 1.05 [1.01-1.09]; P = 0.017) and glycated hemoglobin (1.17 [1.01-1.37]; P = 0.036) were significantly associated with the presence of carotid plaque.

CONCLUSIONS

The positive correlation of serum GA with the presence of carotid plaque in type 2 diabetes suggests that GA will serve as a useful clinical marker for predicting diabetic cardiovascular complications.

Calculation of HbA1c and glycated albumin from serially measured self-monitored blood glucose in patients with type 1 diabetes mellitus

BACKGROUND

Both HbA1c and glycated albumin (GA) values are influenced by weighted mean of preceding blood glucose levels depending on each half-life. Based on this principle, we developed formulas for calculation of HbA1c and GA using data from self-monitored blood glucose (SMBG). We also calculated HbA1c and GA in diabetic patients using the developed formulas.

METHODS

This study included 9 patients with childhood-onset type 1 diabetes mellitus (6 males and 3 females; aged 11.4±4.2 y). From the weekly mean blood glucose (MBG) values obtained by the SMBG data during the previous 20 weeks, we calculated HbA1c and GA using the developed formulas and compared the calculated values with the measured values (n=42).

RESULTS

The measured and the calculated values of HbA1c were 8.5±0.9% and 8.3±1.2%, respectively. The measured and the calculated values of GA were 24.9±3.7% and 26.4±4.0%, respectively. There were strong positive correlations between both values of HbA1c and GA (P<0.0001).

CONCLUSIONS

The calculated HbA1c and GA values using the developed formulas from the SMBG data were generally in agreement with the measured values. Using the calculation formulas, the values of HbA1c and GA could be estimated from serially measured SMBG data.

Optimal hemoglobin A1C Cutoff Value for Diagnosing type 2 diabetes mellitus in Korean adults

Commonly used tests for the diagnosis of diabetes include measurements of fasting plasma glucose levels and the oral glucose tolerance test (OGTT). Recently, a hemoglobin A1C (A1C) level of 6.5% has been included as a criterion for diabetes diagnosis by the American Diabetes Association. We aimed to determine appropriate A1C cutoff values for identifying patients with diabetes or prediabetes, including impaired glucose tolerance and impaired fasting glucose among Korean adults and to determine whether these cutoffs vary according to age. We recruited 4616 adults without a history of diabetes from 10 university hospitals. A 75-g OGTT and A1C sampling were performed in all examinees. Pointwise area under the receiver operating characteristic curve was used to evaluate the diagnostic accuracy of the A1C cutoff. An A1C threshold of 6.1% proved to be the optimal limit for diagnosing diabetes, with 63.8% sensitivity and 88.1% specificity. The cutoff value increased with age (5.9% in 18-39 years, 6.2% in 40-64 years, and 6.4% in older than 65 years) and were similar for men and women. An A1C cutoff of 5.7% had reasonable sensitivity (48.6%) and specificity (65.7%) for the identification of prediabetes. Further prospective studies should be carried out to determine whether the application of age-specific diagnostic criteria is appropriate.

Diabetes management in the kidney patient

Hyperglycemia management in chronic kidney disease (CKD) patients presents difficult challenges, partly due to the complexity involved in treating these patients, and partly due to lack of data supporting benefits of tight glycemic control. While hyperglycemia is central to the pathogenesis and management of diabetes, hypoglycemia and glucose variability also contribute to outcomes. Multiple agents with different mechanisms of action are now available; some can lower glucose levels without the risk of hypoglycemia. This article reviews metabolic changes present in kidney impairment/failure, current views about glycemic goals, and treatment options for the diabetic patient with CKD.

Ethnicity modifies the relation between fasting plasma glucose and HbA1c in Indians, Malays and Chinese

AIMS

To study whether HbA(1c) , and its relationship with fasting plasma glucose, was significantly different among Chinese, Malays and Indians in Singapore.

METHODS

A sample of 3895 individuals without known diabetes underwent detailed interview and health examination, including anthropometric and biochemical evaluation, between 2004 and 2007. Pearson's correlation, analysis of variance and multiple linear regression analyses were used to examine the influence of ethnicity on HbA(1c) .

RESULTS

As fasting plasma glucose increased, HbA(1c) increased more in Malays and Indians compared with Chinese after adjustment for age, gender, waist circumference, serum cholesterol, serum triglyceride and homeostasis model assessment of insulin resistance (P-interaction < 0.001). This translates to an HbA(1c) difference of 1.1 mmol/mol (0.1%, Indians vs. Chinese), and 0.9 mmol/mol (0.08%, Malays vs. Chinese) at fasting plasma glucose 5.6 mmol/l (the American Diabetes Association criterion for impaired fasting glycaemia); and 2.1 mmol/mol (0.19%, Indians vs. Chinese) and 2.6 mmol/mol (0.24%, Malays vs. Chinese) at fasting plasma glucose 7.0 mmol/l, the diagnostic criterion for diabetes mellitus.

CONCLUSIONS

Using HbA(1c) in place of fasting plasma glucose will reclassify different proportions of the population in different ethnic groups. This may have implications in interpretation of HbA(1c) results across ethnic groups and the use of HbA(1c) for diagnosing diabetes mellitus.

Characteristics of children with type 1 diabetes and persistent suboptimal glycemic control

OBJECTIVE

This study aims to determine the relationship between the duration of persistent poor glycemic control in type 1 diabetes mellitus (T1DM) children and the likelihood of subsequent improvement.

METHODS

A retrospective cohort study was conducted on T1DM patients aged 6-18 years, followed for at least six visits at Children's National Medical Center (Washington, DC) with at least one hemoglobin A1c (HbA1c) ≥ 10% after the first year since the initial visit (n=151). Medical records of patients with subsequently improved glycemic control were reviewed (n=39).

RESULTS

Patients aged 12-18 years, females, and Medicaid patients were twice as likely to be in persistently poor control as patients aged 6-11 years, males, and privately insured patients, respectively. Each additional visit with HbA1c ≥ 10% and one percentage point increase in the mean HbA1c reduced the likelihood of subsequent improvement by 20% and 50%, respectively. Of the 39 patients with improved control, only 5 (13%) sustained their improvement for ≥ 2 years. Multiple contributing factors for improved control were identified, but no one factor explained improved control in > 25% of patients.

CONCLUSION

This study suggests that the longer the duration of poor control, the more difficult it is to reverse the underlying factors of poor diabetes management. Strategies to improve regular clinic attendance along with reinforcement of changes which resulted in improved control are critical. Adolescents, females, and Medicaid patients in particular should be targeted for sustained intervention.

Relation of fasting and postprandial and plasma glucose with hemoglobinA1c in diabetics

CONTEXT

Control of plasma glucose could prevent the progression of most of the complications of diabetes and hemoglobinA1c (HbA1c) is the most important criterion controlling these long-term complications.

AIMS

This study was performed to assess the effect of fasting plasma glucose (FPG) and two- hour postprandial plasma glucose (2hpp) levels on HbA1c.

MATERIALS AND METHODS

In this descriptive, cross-sectional study; 300 patients were enrolled, assessed, and followed up at the clinic of the Diabetic Center of the University of Medical Science, Hamadan, Iran. All studied patients were diagnosed type 1 or 2 diabetes mellitus. Sampling was performed; we assessed FPG and 2hpp plasma glucose at baseline and at every two weeks to one month-as needed. HbA1c was assessed at the end of study. Results were analyzed by Pierson Covariance and Multiple Regression methods.

RESULTS

The mean plasma glucose in three groups of HbA1c (good to fair) were 148.5 +/- 56.80 mg/dl at fasting, and 199.70 +/- 53.01 mg/dl at two hours after breakfast (2hpp) and mean concentration of HbA1c were 8.41 +/- 1.1 %. The plasma glucose level and HbA1c were 0.312 for fasting and, 0.416 for 2hpp at covariant value.

CONCLUSION

The postprandial (after breakfast) plasma glucose has closer association to glycosylated hemoglobin than fasting plasma glucose, therefore evaluating postprandial plasma glucose should be our focus.

Implications of using hemoglobin A1C for diagnosing diabetes mellitus

Until 2010, the diagnosis of diabetes mellitus was based solely on glucose concentration, but the American Diabetes Association (ADA) recommendations now include a new criterion: hemoglobin A1C ≥6.5%. Because this change may have significant implications for diabetes diagnosis, we conducted a comprehensive literature review including peer-reviewed articles not referenced in the ADA report. We conclude that A1C and plasma glucose tests are frequently discordant for diagnosing diabetes. A1C ≥6.5% identifies fewer individuals as having diabetes than glucose-based criteria. Convenience of A1C test might increase the number of patients diagnosed, but this is unproven. Diagnostic cut-points for both glucose and A1C are based on consensus judgments regarding optimal sensitivity and specificity for the complications of hyperglycemia. A1C may not accurately reflect levels of glycemia in some situations, but in comparison with glucose measurements, it has greater analytic stability and less temporal variability. When choosing a diagnostic test for diabetes, the limitations of each choice must be understood. Clinical judgment and consideration of patient preference are required to appropriately select among the diagnostic alternatives.

Relationship between A1C and glucose levels in the general Dutch population: the new Hoorn study

OBJECTIVE

To investigate the relationship among A1C, fasting plasma glucose (FPG), and 2-h postload plasma glucose in the Dutch general population and to evaluate the results of using A1C for screening and diagnosis of diabetes.

RESEARCH DESIGN AND METHODS

In 2006-2007, 2,753 participants of the New Hoorn Study, aged 40-65 years, who were randomly selected from the population of Hoorn, the Netherlands, underwent an oral glucose tolerance test (OGTT). Glucose status (normal glucose metabolism [NGM], intermediate hyperglycemia, newly diagnosed diabetes, and known diabetes) was defined by the 2006 World Health Organization criteria. Spearman correlations were used to investigate the agreement between markers of hyperglycemia, and a receiver operating characteristic (ROC) curve was calculated to evaluate the use of A1C to identify newly diagnosed diabetes.

RESULTS

In the total population, the correlations between fasting plasma glucose and A1C and between 2-h postload plasma glucose and A1C were 0.46 and 0.33, respectively. In patients with known diabetes, these correlations were 0.71 and 0.79. An A1C level of > or =5.8%, representing 12% of the population, had the highest combination of sensitivity (72%) and specificity (91%) for identifying newly diagnosed diabetes. This cutoff point would identify 72% of the patients with newly diagnosed diabetes and include 30% of the individuals with intermediate hyperglycemia.

CONCLUSIONS

In patients with known diabetes, correlations between glucose and A1C are strong; however, moderate correlations were found in the general population. In addition, based on the diagnostic properties of A1C defined by ROC curve analysis, the advantage of A1C compared with OGTT for the diagnosis of diabetes is limited.

Genetic variant in HK1 is associated with a proanemic state and A1C but not other glycemic control-related traits

OBJECTIVE

A1C is widely considered the gold standard for monitoring effective blood glucose levels. Recently, a genome-wide association study reported an association between A1C and rs7072268 within HK1 (encoding hexokinase 1), which catalyzes the first step of glycolysis. HK1 deficiency in erythrocytes (red blood cells [RBCs]) causes severe nonspherocytic hemolytic anemia in both humans and mice.

RESEARCH DESIGN AND METHODS

The contribution of rs7072268 to A1C and the RBC-related traits was assessed in 6,953 nondiabetic European participants. We additionally analyzed the association with hematologic traits in 5,229 nondiabetic European individuals (in whom A1C was not measured) and 1,924 diabetic patients. Glucose control-related markers other than A1C were analyzed in 18,694 nondiabetic European individuals. A type 2 diabetes case-control study included 7,447 French diabetic patients.

RESULTS

Our study confirms a strong association between the rs7072268-T allele and increased A1C (beta = 0.029%; P = 2.22 x 10(-7)). Surprisingly, despite adequate study power, rs7072268 showed no association with any other markers of glucose control (fasting- and 2-h post-OGTT-related parameters, n = 18,694). In contrast, rs7072268-T allele decreases hemoglobin levels (n = 13,416; beta = -0.054 g/dl; P = 3.74 x 10(-6)) and hematocrit (n = 11,492; beta = -0.13%; P = 2.26 x 10(-4)), suggesting a proanemic effect. The T allele also increases risk for anemia (836 cases; odds ratio 1.13; P = 0.018).

CONCLUSIONS

HK1 variation, although strongly associated with A1C, does not seem to be involved in blood glucose control. Since HK1 rs7072268 is associated with reduced hemoglobin levels and favors anemia, we propose that HK1 may influence A1C levels through its anemic effect or its effect on glucose metabolism in RBCs. These findings may have implications for type 2 diabetes diagnosis and clinical management because anemia is a frequent complication of the diabetes state.

Association of A1C and fasting plasma glucose levels with diabetic retinopathy prevalence in the U.S. population: Implications for diabetes diagnostic thresholds

OBJECTIVE

To examine the association of A1C levels and fasting plasma glucose (FPG) with diabetic retinopathy in the U.S. population and to compare the ability of the two glycemic measures to discriminate between people with and without retinopathy.

RESEARCH DESIGN AND METHODS

This study included 1,066 individuals aged >or=40 years from the 2005-2006 National Health and Nutrition Examination Survey. A1C, FPG, and 45 degrees color digital retinal images were assessed. Retinopathy was defined as a level >or=14 on the Early Treatment Diabetic Retinopathy Study severity scale. We used joinpoint regression to identify linear inflections of prevalence of retinopathy in the association between A1C and FPG.

RESULTS

The overall prevalence of retinopathy was 11%, which is appreciably lower than the prevalence in people with diagnosed diabetes (36%). There was a sharp increase in retinopathy prevalence in those with A1C >or=5.5% or FPG >or=5.8 mmol/l. After excluding 144 people using hypoglycemic medication, the change points for the greatest increase in retinopathy prevalence were A1C 5.5% and FPG 7.0 mmol/l. The coefficients of variation were 15.6 for A1C and 28.8 for FPG. Based on the areas under the receiver operating characteristic curves, A1C was a stronger discriminator of retinopathy (0.71 [95% CI 0.66-0.76]) than FPG (0.65 [0.60 - 0.70], P for difference = 0.009).

CONCLUSIONS

The steepest increase in retinopathy prevalence occurs among individuals with A1C >or=5.5% and FPG >or=5.8 mmol/l. A1C discriminates prevalence of retinopathy better than FPG.

HbA1c: how do we measure it and what does it mean?

PURPOSE OF REVIEW

Description of recent developments in the standardization of HbA1c measurement and interpretation of HbA1c results.

RECENT FINDINGS

HbA1c is extensively used in the management of patients with diabetes. The two major schemes to standardize HbA1c produce values that differ substantially. A prospective, multinational study revealed a linear correlation between HbA1c and average blood glucose. Some, but not all, assay methods are able to accurately measure HbA1c in individuals with common hemoglobin variants.

SUMMARY

Progress in standardization of methods for HbA1c measurement has significantly reduced variation among different methods. The improved accuracy could allow HbA1c to be used for screening and diagnosis of diabetes. A consensus document recommends that HbA1c be reported in both NGSP (%) and IFCC (mmol/mol) units. HbA1c results can be translated into estimated average glucose (eAG), which could be reported in addition to HbA1c.