More evidence of the problems of using HbA1c for diagnosing diabetes? The known knowns, the known unknowns and the unknown unknowns

Association between glycemia risk index and arterial stiffness in type 2 diabetes

AIM

This study aims to investigate the association of glycemia risk index (GRI), a novel composite metric derived from continuous glucose monitoring (CGM), with arterial stiffness in patients with type 2 diabetes.

MATERIALS AND METHODS

A total of 342 adults with type 2 diabetes were enrolled between April and June 2023 from 11 communities in Shanghai, China. Medical examinations, including measurements of anthropometric parameters, blood pressure, and venous blood samples were conducted. Brachial-ankle pulse wave velocity (baPWV) was examined to evaluate arterial stiffness. All the participants underwent a 14 day CGM recording and GRI was calculated from the CGM data.

RESULTS

The mean age was 70.3 ± 6.8 years, and 162 (47.4%) were male. Participants with a higher baPWV had significantly higher levels of GRI and hyperglycemia component (both P for trend < 0.05). Linear regression revealed the significant positive linear associations of the GRI with baPWV in unadjusted or adjusted models (All P < 0.05). In the multivariable logistic analysis, each increase in the GRI quartile was associated with a 1.30-fold (95% CI 1.01-1.68, P for trend < 0.05) higher prevalence of increased arterial stiffness after adjustment for age, sex, BMI, diabetes duration, current smoking status, blood pressure, and lipid profile. Subgroup analyses showed that the association between the GRI quartiles and increased arterial stiffness was stronger among participants with a diabetes duration ≥15 years (P for interaction = 0.014).

CONCLUSION

Glycemia risk index assessed by continuous glucose monitoring is associated with increased arterial stiffness in type 2 diabetes.

Glycated haemoglobin (HbA1c) in mid-pregnancy and perinatal outcomes

Background

Maternal diabetes is a well-known risk factor for pregnancy complications. Possible links between long-term maternal blood sugar in the normal range and pregnancy complications are less well described.

Methods

We assayed glycated haemoglobin (HbA1c) in blood samples collected around the 18th week of pregnancy for 2937 singleton pregnancies in the Norwegian Mother, Father and Child Cohort Study (2000–09). Perinatal outcomes (gestational length, birthweight, birth length and head circumference, large-for-gestational age, small-for-gestational age, congenital malformations, preterm delivery and preeclampsia) were obtained from medical records. We tested associations using linear and log-binomial regression, adjusting for maternal age, body mass index (BMI) and smoking.

Results

Size at birth increased modestly but linearly with HbA1c. Birthweight rose 0.10 standard deviations [95% confidence interval (CI): 0.03, 0.16], for each 5-mmol/mol unit increase in HbA1c, corresponding to about 40 g at 40 weeks of gestation. Large-for-gestational age rose 23% (95% CI: 1%, 50%) per five-unit increase. Other pregnancy complications increased in non-linear fashion, with strongest associations within the top quartile of HbA1c (>35 mmol/mol or >5.4%). Per unit HbA1c within the top quartile, preterm delivery increased by 14% (95% CI: 1%, 31%), preeclampsia increased by 20% (95% CI: 5%, 37%) and gestational duration decreased by 0.7 days (95% CI: −1.0, −0.3).

Conclusions

Among women with no recorded diabetes, higher HbA1c levels at 18 gestational weeks were associated with important perinatal outcomes independent of mother’s age, smoking or BMI.

The prevalence and correlates of pre-diabetes in middle- to older-aged Irish adults using three diagnostic methods

BACKGROUND AND OBJECTIVES

Type 2 diabetes is a leading cause of death and disability worldwide and pre-diabetes is a strong predictor of diabetes development. To date, studies estimating the prevalence of pre-diabetes in the Irish population are sparse and conflicting. Monitoring the prevalence of pre-diabetes and a knowledge of associated factors is required to inform policies and to prevent development of type 2 diabetes. Therefore, this research examined the prevalence and correlates of pre-diabetes in a sample of middle- to older-aged Irish adults using three different methods for diagnosis.

MATERIALS AND METHODS

The Mitchelstown Cohort Rescreen (2016/17) was a follow-up, cross-sectional study of the Mitchelstown Cohort Study (2010/11). 1,378 participants were recruited from a random sample of patients attending a single primary care centre. Pre-diabetes was defined using three diagnostic criteria: American Diabetes Association (ADA) glycated haemoglobin A1c (HbA1c) cut-offs between 5.7%-6.4% (39-46 mmol/mol), World Health Organization International Expert Committee (WHO-IEC) HbA1c cut-offs between 6.0%-6.4% (42-46 mmol/mol) and ADA fasting plasma glucose (FPG) cut-offs between 5.6-6.9 mmol/l. Univariate and multivariable logistic regression analyses were used to determine factors associated with pre-diabetes.

RESULTS

The prevalence of pre-diabetes was found to be 43.9% (95% CI: 41.2%─46.5%), 14.5% (95% CI: 12.7%─16.5%) and 15.8% (95% CI: 13.9%─17.8%) according to HbA1c ADA, HbA1c WHO-IEC and FPG ADA definitions, respectively. Depending on diagnostic method, factors associated with pre-diabetes in univariate analyses included sex, age, marital status, health rating, education and poor diet quality. In multivariable analysis, subjects classified by the FPG ADA pre-diabetes criterion displayed the least optimal metabolic profile defined by overweight and obesity (OR = 2.88, 95% CI: 1.53-5.43), hypertension (OR = 2.27, 95% CI: 1.51-3.40) and low high-density lipoprotein cholesterol concentrations (OR = 1.75, 95% CI: 1.07-2.87).

CONCLUSIONS

The discordance between prevalence estimates according to method of diagnosis is concerning. A National Diabetes Prevention Programme is currently being developed in Ireland. Monitoring the prevalence of pre-diabetes over time will be important to assess the effectiveness of this programme. This study will inform national decision-makers on which definition of pre-diabetes to use for monitoring purposes.

Glycated Albumin for Glycemic Control in T2DM Population: A Multi-Dimensional Evaluation

Purpose

To investigate the glycated albumin (GA) introduction implications, as an add-on strategy to traditional glycemic control (Hb1Ac and fasting plasma glucose – FPG) instruments, considering insulin-naïve individuals with type 2 diabetes mellitus (T2DM), treated with oral therapies.

Methods

A Health Technology Assessment was conducted in Italy, as a multi-dimensional approach useful to validate any innovative technology. The HTA dimensions, derived from the EUnetHTA Core Model, were deployed by means of literature evidence, health economics tools and qualitative questionnaires, filled-in by 15 professionals.

Results

Literature stated that the GA introduction could lead to a higher number of individuals achieving therapeutic success after 3 months of therapy (97.0% vs 71.6% without GA). From an economic point of view, considering a projection of 1,955,447 T2DM insulin-naïve individuals, potentially treated with oral therapy, GA introduction would imply fewer individuals requiring a therapy switch (−89.44%), with a 1.06% in costs reduction, on annual basis, thus being also the preferable solution from a cost-effectiveness perspective (cost-effectiveness value: 237.74 vs 325.53). According to experts opinions, lower perceptions on GA emerged with regard to equity aspects (0.13 vs 0.72, p-value>0.05), whereas it would improve both individuals (2.17 vs 1.33, p-value=0.000) and caregivers quality of life (1.50 vs 0.83, p-value=0.000). Even if in the short term, GA required additional investments in training courses (−0.80 vs 0.10, p-value = 0.036), in the long run, GA could become the preferable technology (0.30 vs 0.01, p-value=0.018) from an organisational perspective.

Conclusion

Adding GA to traditional glycaemic control instruments could improve the clinical pathway of individuals with T2DM, leading to economic and organisational advantages for both hospitals and National Healthcare Systems.

Paradigm Shifts in the Management of Diabetes in Pregnancy: The Importance of Type 2 Diabetes and Early Hyperglycemia in Pregnancy: The 2020 Norbert Freinkel Award Lecture

For over 50 years, the diagnosis of gestational diabetes mellitus (GDM) has been based upon an oral glucose tolerance test at 24-28 weeks' gestation. This is the time during pregnancy when insulin resistance is increasing and hyperglycemia develops among those with insufficient insulin secretory capacity to maintain euglycemia. The Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study and the two major randomized controlled trials of treating GDM are based upon recruitment of women at this time during pregnancy. Meanwhile, the increasing prevalence of type 2 diabetes in pregnancy, with its significant risk of adverse pregnancy outcomes, has led to a need to identify undiagnosed diabetes as near to conception as possible. Screening for undiagnosed diabetes early in pregnancy also identifies women with hyperglycemia less than overt diabetes, yet at increased risk of adverse pregnancy outcomes. Such women are more insulin resistant-with higher blood pressure, triglycerides, perinatal mortality, and neonatal hypoglycemia with a greater need for insulin treatment-than those with GDM diagnosed at 24-28 weeks' gestation. Currently, there is uncertainty over how to diagnose GDM early in pregnancy and the benefits and harms from using the current management regimen. Randomized controlled trials testing the criteria for, and treatment of, GDM early in pregnancy are urgently needed to address this existing equipoise. In the meantime, the importance of early or "prevalent GDM" (i.e., mild hyperglycemia present from early [before] pregnancy) warrants interim criteria and thresholds for medication, which may differ from those in use for GDM diagnosed at 24-28 weeks' gestation.

Options for screening for gestational diabetes mellitus during the SARS-CoV-2 pandemic

The balance between avoiding severe acute respiratory syndrome coronavirus‐2 contagion and reducing wider clinical risk is unclear for gestational diabetes mellitus (GDM) testing. Recent recommendations promote diagnostic approaches that limit collection but increase undiagnosed GDM, which potentially increases adverse pregnancy outcome risks. The most sensitive approach to detecting GDM at 24–28 weeks beyond the two‐hour oral glucose tolerance test (OGTT) is a one‐hour OGTT (88% sensitivity). Less sensitive approaches use fasting glucose alone (≥5.1 mmol/L: misses 44–54% GDM) or asking ~20% of women for a second visit (fasting glucose 4.7–5.0 mmol/L (62–72% sensitive)). Choices should emphasise local and patient decision‐making.

Update on biomarkers of glycemic control

Attaining and maintaining good glycemic control is a cornerstone of diabetes care. The monitoring of glycemic control is currently based on the self-monitoring of blood glucose (SMBG) and laboratory testing for hemoglobin A1c (HbA1c), which is a surrogate biochemical marker of the average glycemia level over the previous 2-3 mo period. Although hyperglycemia is a key biochemical feature of diabetes, both the level of and exposure to high glucose, as well as glycemic variability, contribute to the pathogenesis of diabetic complications and follow different patterns in type 1 and type 2 diabetes. HbA1c provides a valuable, standardized and evidence-based parameter that is relevant for clinical decision making, but several biological and analytical confounders limit its accuracy in reflecting true glycemia. It has become apparent in recent years that other glycated proteins such as fructosamine, glycated albumin, and the nutritional monosaccharide 1,5-anhydroglucitol, as well as integrated measures from direct glucose testing by an SMBG/continuous glucose monitoring system, may provide valuable complementary data, particularly in circumstances when HbA1c results may be unreliable or are insufficient to assess the risk of adverse outcomes. Long-term associations of these alternative biomarkers of glycemia with the risk of complications need to be investigated in order to provide clinically relevant cut-off values and to validate their utility in diverse populations of diabetes patients.

A Perspective on the Accuracy of Blood Glucose Meters During Pregnancy

Blood glucose monitoring is fundamental for hyperglycemia management during pregnancy, but are the devices up to the job? Studies assessing the accuracy of 10 commercially available glucose meters during pregnancy showed that although >98-99% of the meter values were in the acceptable zones of the error grid for the majority of the meters, the meter performance varied, with the majority showing positive bias and a few showing minimal negative bias. The mean difference between meter and laboratory plasma values varied between -0.33 and 0.73 mmol/L. Three meters showed deviations from laboratory results with a change in maternal hematocrit levels. No meters had a total analytical error <5%, and no studies evaluated meters using recent International Organization for Standardization 15197:2013 criteria. The Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT) recently showed that an antenatal continuous glucose monitoring system (CGMS), as an adjunct to capillary monitoring, was associated with a lower incidence of large-for-gestational-age babies, fewer neonatal intensive care unit admissions (>24 h), and a lower incidence of neonatal hypoglycemia. The flash glucose monitoring system shows good accuracy in pregnant women but has not been marketed widely in the U.S. We suggest that meters cannot be assumed to be sufficiently accurate during pregnancy and that manufacturers should ensure a total error <5%, with bias and imprecision <2% during pregnancy. Large studies are needed to evaluate the usefulness of CGMS among pregnant women with type 2 diabetes and gestational diabetes mellitus.

Should we screen for type 2 diabetes among asymptomatic individuals? Yes

RCTs of whether screening asymptomatic individuals for undiagnosed diabetes results in reduced mortality or has other benefits have been suggestive, but inconclusive. In this issue of Diabetologia, two additional controlled studies (DOIs: 10.1007/s00125-017-4323-2 and 10.1007/s00125-017-4299-y ) that investigated whether screening for type 2 diabetes in asymptomatic individuals is associated with a reduction in mortality are presented. Treating diabetes early, and identifying and treating impaired glucose tolerance, are of benefit, and economic modelling indicates such screening is cost-effective. Now that such screening is already underway in many countries, new data, along with the existing evidence, suggests opportunistic screening is the best way forward. More research is needed, however, on how best to screen and how to improve risk-factor control once dysglycaemia is detected.

Screening and Treatment for Early-Onset Gestational Diabetes Mellitus: a Systematic Review and Meta-analysis

We conducted a systematic review to evaluate the current evidence for screening and treatment for early-onset gestational diabetes mellitus (GDM) RECENT FINDINGS: Many of the women with early GDM in the first trimester do not have evidence of hyperglycemia at 24-28 weeks' gestation. A high proportion (15-70%) of women with GDM can be detected early in pregnancy depending on the setting, criteria used and screening strategy. However, there remains no good evidence for any of the diagnostic criteria for early-onset GDM. In a meta-analysis of 13 cohort studies, perinatal mortality (relative risk (RR) 3.58 [1.91, 6.71]), neonatal hypoglycemia (RR 1.61 [1.02, 2.55]), and insulin use (RR 1.71 [1.45, 2.03]) were greater among early-onset GDM women compared to late-onset GDM women, despite treatment. Considering the high likelihood of benefit from treatment, there is an urgent need for randomized controlled trials that investigate any benefits and possible harms of treatment of early-onset GDM.

Glycated albumin: from biochemistry and laboratory medicine to clinical practice

This review summarizes current knowledge about glycated albumin. We review the changes induced by glycation on the properties of albumin, the pathological implications of high glycated albumin levels, glycated albumin quantification methods, and the use of glycated albumin as a complementary biomarker for diabetes mellitus diagnosis and monitoring and for dealing with long-term complications. The advantages and limits of this biomarker in different clinical settings are also discussed.

HbA1c alone is a poor indicator of cardiometabolic risk in middle-aged subjects with pre-diabetes but is suitable for type 2 diabetes diagnosis: a cross-sectional study

Objectives

Glycated haemoglobin A_1c (HbA_1c) measurement is recommended as an alternative to fasting plasma glucose (FPG) for the diagnosis of pre-diabetes and type 2 diabetes. However, evidence suggests discordance between HbA_1c and FPG. In this study we examine a range of metabolic risk features, pro-inflammatory cytokines, acute-phase response proteins, coagulation factors and white blood cell counts to determine which assay more accurately identifies individuals at increased cardiometabolic risk.

Materials and Methods

This was a cross-sectional study involving a random sample of 2,047 men and women aged 46-73 years. Binary and multinomial logistic regression were employed to examine risk feature associations with pre-diabetes [either HbA_1c levels 5.7-6.4% (39-46 mmol/mol) or impaired FPG levels 5.6-6.9 mmol/l] and type 2 diabetes [either HbA_1c levels >6.5% (>48 mmol/mol) or FPG levels >7.0 mmol/l]. Receiver operating characteristic curve analysis was used to evaluate the ability of HbA_1c to discriminate pre-diabetes and diabetes defined by FPG.

Results

Stronger associations with diabetes-related phenotypes were observed in pre-diabetic subjects diagnosed by FPG compared to those detected by HbA_1c. Individuals with type 2 diabetes exhibited cardiometabolic profiles that were broadly similar according to diagnosis by either assay. Pre-diabetic participants classified by both assays displayed a more pro-inflammatory, pro-atherogenic, hypertensive and insulin resistant profile. Odds ratios of having three or more metabolic syndrome features were also noticeably increased (OR: 4.0, 95% CI: 2.8-5.8) when compared to subjects diagnosed by either HbA_1c (OR: 1.4, 95% CI: 1.2-1.8) or FPG (OR: 3.0, 95% CI: 1.7-5.1) separately.

Conclusions

In middle-aged Caucasian-Europeans, HbA_1c alone is a poor indicator of cardiometabolic risk but is suitable for diagnosing diabetes. Combined use of HbA_1c and FPG may be of additional benefit for detecting individuals at highest odds of type 2 diabetes development.

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.