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

Ethnicity Affects A1C Levels in Patients With Diagnosed Type 2 Diabetes in Southern Israel

Purpose

To assess whether ethnicity affects the association between A1C and fasting glucose in people with type 2 diabetes.

Methods

This investigation was an epidemiological, cross-sectional study based on computerized medical records of the Southern District of Clalit Health Services. The study population comprised patients ≥40 years of age with type 2 diabetes who underwent blood tests between 8 August 2015 and 20 July 2020. A normal-error multiple linear regression model was used to assess differences in associations among ethnic groups (i.e., Arabs, Ethiopian Jews, and non-Ethiopian Jews) and A1C.

Results

A total of 59,432 patients with type 2 diabetes were included in the study. Of these, 1,804 were Jews of Ethiopian origin, 49,296 were non-Ethiopian Jews, and 8,332 were Arabs. Compared with non-Ethiopian Jews, A1C levels were increased by 0.1% (1 mmol/mol) among Ethiopian Jews and by 0.3% (3 mmol/mol) among Arabs. Ethnicity was a strong predictor of A1C, explaining 0.6% of its variance. An A1C level of 7% (53 mmol/mol) correlated with fasting glucose levels of 141, 136, and 126 mg/dL in non-Ethiopian Jews, Ethiopian Jews, and Arabs, respectively.

Conclusion

Ethnic differences in A1C should be considered by clinicians, researchers, and policymakers.

Glycated haemoglobin trajectories and one-year risk of potentially avoidable hospitalisations among adult type 2 diabetes patients seeking care at specialist outpatient clinics of a tertiary hospital: a cohort study

AIM

To evaluate the association between trajectories of glycated haemoglobin (HbA1c) and potentially avoidable hospitalisations (PAH).

METHODS

We performed a cohort study in a tertiary hospital in Singapore among adult type 2 diabetes patients with ≥3HbA1c tests over two years. Then, we followed up for one year after the last HbA1c reading. Glycaemic control was analysed by (1)HbA1c trajectories through group-based trajectory modelling, and (2)mean HbA1c. PAH was defined using the Agency of Healthcare Research and Quality criteria, categorising as overall, acute, chronic, diabetes-composites.

RESULTS

A total of 14923 patients (mean age:62.9±12.8 years;55.2% men)were included. Four HbA1c trajectories were observed; low-stable(n=9854,66.0%), moderate-stable(n=3125,20.9%), high-decrease(n=1017,6.8%) and high-persistent(n=927,6.2%). Compared to the low-stable trajectory, one-year risk ratio(RR) and 95%CI, respectively for moderate-stable, high-decrease and high-persistent trajectories were as follows:(1)overall PAH:1.15(1.00-1.31),1.53(1.31-1.80),1.96(1.58-2.43);(2)diabetes PAH:1.30(1.04-1.64),1.98(1.55-2.53),2.24(1.59-3.15);(3)acute PAH:1.14(0.90-1.44),1.29(0.95-1.77),1.75(1.17-2.62); and (4)chronic PAH:1.21(1.02-1.43),1.62(1.34-1.97),2.14(1.67-2.75). Mean HbA1c was significantly associated with overall and chronic-composites of PAH whilst evidence of a non-linear relationship with diabetes-composite of PAH was noted.

CONCLUSION

Patients with high-decrease trajectory had a risk lower than those with persistently-high HbA1c, highlighting that a greater risk of hospitalisation conferred by poor glycaemic control is potentially reversible. Determining HbA1c trajectories could help to identify the high-risk individuals for targeted and intensive management to improve care and reduce hospitalisations.

Establishing Trimester-Specific Haemoglobin A1c Reference Intervals in Pregnant Women: A retrospective study of healthy South Asian women with normal pregnancy outcomes

Objectives

This study aimed to define trimester-specific haemoglobin A1c (HbA1c) reference intervals in healthy, pregnant South Asian women.

Methods

This retrospective study was conducted at St. Stephen's Hospital, Delhi, India, between January 2011 and December 2016. Healthy pregnant women were compared to a control group of healthy non-pregnant women. Pregnant participants had term deliveries of babies with appropriate gestational weights. The HbA1c levels were calculated in terms of non-parametric 2.5 and 97.5 percentiles for women in first (T1), second (T2) and third (T3) trimester groups. Statistical tests were used to obtain the normal HbA1c reference values and were considered significant when P <0.05.

Results

This study included a total of 1,357 healthy pregnant women and a control group of 67 healthy, non-pregnant women. Pregnant women had a median HbA1c of 4.8% (4-5.5%) or 32 mmol/mol (20-39 mmol/mol); non-pregnant women had a median HbA1c of 5.1% (4-5.7%) or 29 mmol/mol (20-37 mmol/mol; P <0.001). The HbA1c levels for the T1, T2 and T3 groups were 4.9% (4.1-5.5%) or 30 mmol/mol (21-37 mmol/mol), 4.8% (4.5-5.3%) or 29 mmol/mol (20-34 mmol/mol) and 4.8% (3.9-5.6%) or 29 mmol/mol (19-38 mmol/mol), respectively. The HbA1c values were significant when comparing T1 versus T2 (P <0.001), T1 versus T3 (P = 0.002) and T1 versus the non-pregnant group (P = 0.001). However, T2 versus T3 was not significant (P = 0.111).

Conclusion

Compared to non-pregnant women, HbA1c levels were lower in pregnant women, despite women in the T2 and T3 groups having a higher body mass index than the women in the T1 and non-pregnant groups. Further research is recommended to understand the factors responsible and validate these findings.

Ethnic Variability in Glucose and Insulin Response to Rice Among Healthy Overweight Adults: A Randomized Cross-Over Study

BACKGROUND

The influence of ethnicity on postprandial glucose and insulin responses has been reported earlier and rice is a major contributor to the overall glycaemic load of Asian and Arab diets. This study aims to compare postprandial glycaemic and insulinaemic responses to rice among healthy overweight Asian, Arab and European participants.

METHODS

In a randomized crossover design, 47 healthy overweight participants (23 Asian, 16 Arab, and 8 European) consumed 75 grams of glucose beverage or ate 270 grams of cooked basmati rice (75 g of available carbohydrate) on two separate occasions, separated by a one 1-week washout period. Blood glucose and insulin levels were determined at fasting 0 (fasting), 30, 60, and 120 minutes and used to determine the incremental area under the curve (iAUC).

RESULTS

The three groups were matched on body mass index and gender. Although no differences were noted statistically in most clinical features, a wide range of variation was noted in age, systolic, diastolic blood pressure. The fasting blood glucose and insulin levels were highest among Asians, followed by Arabs and Europeans (p < 0.01). According to the HOMA-IR test and the Matsuda index, Asians have a higher insulin resistance than Arabs or Europeans when consuming a glucose beverage (p < 0.001) and rice (p < 0.01). Postprandial glucose and insulin responses to glucose beverage did not differ between ethnic groups (p = 0.28; p = 0.10). Based on an unadjusted regression model, European participants had significantly lower iAUC-glucose (p = 0.02) and iAUC-insulin (p = 0.01) after rice consumption than Asian participants. In the adjusted model, the difference between the two groups remained for iAUC-insulin (p = 0.04) but not for iAUC-glucose (p = 0.07).

CONCLUSION

Our study found that ethnic differences exist among healthy overweight adults in terms of insulin resistance, glycaemic response and insulinaemic response to rice. As a result of their high insulin resistance, Asian participants had a higher postprandial insulin spike than Europeans after eating rice. These findings could have substantial implications for nutrition recommendations based on ethnicity, particularly for Asians.

HbA1c combined with glycated albumin or 1,5-anhydroglucitol improves the efficiency of diabetes screening in a Chinese population

AIMS

This study aimed to evaluate the ability of HbA_1c combined with glycated albumin (GA) or 1,5-anhydroglucitol (1,5-AG) to detect diabetes in residents of Jiangsu, China.

METHODS

The oral glucose tolerance test (OGTT) was performed on 2184 people in Jiangsu. HbA_1c , GA, 1,5-AG and other serum biochemical parameters were measured. Receiver operating characteristic curves were plotted to determine the optimal thresholds of HbA_1c , GA and 1,5-AG according to the Youden index.

RESULTS

(1) The optimal thresholds of HbA_1c , GA and 1,5-AG for the screening of diabetes were ≥45 mmol/mol (6.3%), ≥13.0% and ≤23.0 μg/ml, respectively. (2) The sensitivities of HbA_1c combined with GA and 1,5-AG were both 85%, higher than that of HbA_1c (70%, p < 0.001).

CONCLUSIONS

This study is suitable for cases where plasma glucose is unavailable. Among the residents of Jiangsu, HbA_1c combined with GA or 1,5-AG can improve the sensitivity of diabetes screening, reduce the miss rate and save the use of OGTT. GA and 1,5-AG are superior in individuals with mild glucose metabolism disorder. GA enhances the detection of diabetes in the nonobese, and 1,5-AG enhances the detection in those with hyperuricaemia.

Glycated haemoglobin in the first trimester: A predictor of gestational diabetes mellitus in pregnant Asian Indian women

AIM

To assess the efficacy of first trimester glycated hemoglobin (HbA1c-FT) in diagnosing or predicting gestational diabetes mellitus (GDM) in Asian Indian women.

METHODS

This retrospective cohort study involved 2275 women who underwent both HbA1c-FT estimation and GDM screening with a one-step 75 g oral glucose tolerance test. Receiver Operating Characteristic (ROC) curve statistics were applied to assess the discriminative ability of HbA1c-FT in GDM diagnosis. A multivariable logistic regression analysis after adjusting for plausible confounders was used to evaluate the independent effect of HbA1c-FT on GDM diagnosis.

RESULTS

The mean HbA1c-FT of GDM (n = 578) and non-GDM women (n = 1697) were 5.04 + 0.04% and 4.9 + 0.37%, respectively (p < 0.001). Compared to women with a HbA1c-FT < 5.2%, the adjusted odds ratio to develop GDM of women with an HbA1c-FT range of 5.2-5.5% and those >5.6% to develop GDM were 1.627 (p < 0.004) and 2.6 (p < 0.001), respectively. The area under the ROC curve to detect GDM was 0.606 (95% CI: 0.519-0.633 p < 0.001), but the sensitivity and specificity of the HbA1c-FT were not sufficient to diagnose, rule in or rule out GDM.

CONCLUSIONS

HbA1c-FT is an independent GDM predictor in Asian Indian women but lacks sufficient sensitivity or specificity for use as a diagnostic test.

Prevalence of diabetes and pre-diabetes in rural Tehri Garhwal, India: influence of diagnostic method

Background

There are few available data regarding the prevalence of diabetes in the sub-Himalayan region of India. The aim of this study was to determine the prevalence of pre-diabetes and diabetes in rural Garhwal based on glycosylated hemoglobin.

Methods

In a cross-sectional survey of 500 adults from five randomly selected villages in Chamba, a mountainous Tehri Garhwal district in Uttarakhand in north-west India, we determined the prevalence of diabetes (hemoglobin (Hb) A_1c ≥ 6.5%) and pre-diabetes (5.7% ≤ HbA_1c ≤ 6.4%). In a sub-sample of those diagnosed with diabetes or pre-diabetes (n = 140), fasting blood glucose (FBG, n = 117) or postprandial blood glucose (PBG, n = 23), and blood hemoglobin concentration, was measured at follow-up.

Results

Based on HbA_1c, 10.0% had diabetes and 56.4% pre-diabetes. Of those diagnosed as diabetic by HbA_1c, 10 of 16 (62.5%) were diagnosed as diabetic by FBG (> 125 mg/dL) or PBG (≥200 mg/dL). In those diagnosed as pre-diabetic by HbA_1c, only 55 of 124 (44.4%) were diagnosed as pre-diabetic by FBG (100–125 mg/dL) or PBG (140–199 mg/dL). A large proportion of these 140 individuals (67.1%) were moderately to severely anemic (Hb < 11.4 mg/dL). The diagnostic gap for pre-diabetes between HbA_1c and FBG/PBG was similar for the groups with and without moderate to severe anemia.

Conclusions

HbA_1c and FBG/PBG have similar diagnostic performance for diabetes in this population. However, many individuals were diagnosed with pre-diabetes by HbA_1c but not FBG/PBG. The relative excess diagnosis of pre-diabetes with HbA_1c does not appear to be explained by anemia, an endemic condition in India. The prognostic significance of diagnosis of pre-diabetes by HbA_1c but not FBG/PBG remains unknown, but merits investigation.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7184-4) contains supplementary material, which is available to authorized users.

Determinants of glycemic control among diabetes mellitus patients in a tertiary clinic in Gaborone, Botswana: findings and implications

BACKGROUND AND AIMS

Glycemic control among patients with diabetes mellitus is associated with a marked reduction of both macrovascular and microvascular complications; however, glycemic control remains an elusive goal worldwide. The aim of this study was to determine factors associated with glycemic control among patients attending a tertiary clinic in Botswana as limited information to date.

METHODS

Cross-sectional study in a tertiary clinic in Gaborone, Botswana. Patients were recruited between 21 July 2015 and 21 September 2015. The majority of the randomly recruited patients (368/380-96.8%) had documentation of glycemic control (HbA1c) within three months of study recruitment and were subsequently included in the analysis. Glycemic control was categorized as desirable, suboptimal and poor if HbA1c was <7%, 7-9% and >9%, respectively. Data were analyzed using SPSS for descriptive statistics including both bivariate and multinomial logistic regression. A value of p < 0.05 was considered statistically significant.

RESULTS

The analyzed study population consisted of 258/368 (70.1%) females with a mean age (SD) of 56.7 ± 13.6 years. Means (SDs) for diabetes duration and glycated hemoglobin were 7.2 ± 7.1 years and 7.97 ± 2.02%, respectively. Of the 368 patients, 136 (36.95%) and 132/368 (35.86%) had desirable and suboptimal glycemic control, respectively. Older age, attending the clinic for more or equal to 3 years and not being on insulin were associated with both desirable and suboptimal glycemic control whereas duration of diabetes between 5 and 10 years was associated with poor glycemic control.

CONCLUSIONS

The majority of patients had poor glycemic control. Older age and not being on insulin were associated with better glycemic control. The fact that patients on insulin had poor glycemic control calls for more research to determine the timing of insulin initiations and dosing schedule factors as these will help to improve overall glycemic control in Botswana and elsewhere.

Optimal first trimester HbA1c threshold to identify Singaporean women at risk of gestational diabetes mellitus and adverse pregnancy outcomes: A pilot study

This pilot study examined the use of early HbA1c in screening for gestational diabetes mellitus and adverse pregnancy outcomes in Singapore. One hundred and fifty-one pregnant women with a gestational age of under 14 weeks had an HbA1c test measured with their antenatal bloods prior to a second trimester oral glucose tolerance test. Patient characteristics and pregnancy outcome data were collected. Gestational diabetes mellitus prevalence was 11%. A receiver operating characteristic curve showed an HbA1c level of 5.2% (33 mmol/mol), had an 82% sensitivity, 72% specificity, 97% negative predictive value and 27% positive predictive value to predict gestational diabetes mellitus. Women with HbA1c of 5.2% (33 mmol/mol) or over 5.2% (33 mmol/mol) were older, had higher BMI and were less likely to be Chinese than those with HbA1c less than 5.2% (33 mmol/mol). There was no difference in pregnancy outcomes. Early HbA1c less than 5.2% (33 mmol/mol) may be useful to exclude low-risk Singaporean women from further testing, while those with HbA1c of 5.2% (33 mmol/mol) or greater would still need a oral glucose tolerance test between 24 and 28 weeks' gestation.

Screening for diabetes with HbA1c: Test performance of HbA1c compared to fasting plasma glucose among Chinese, Malay and Indian community residents in Singapore

The prevalence of diabetes in Singapore is high. Screening to facilitate early detection and intervention has been shown to be cost-effective. Current clinical practice guidelines in Singapore recommend screening with fasting plasma glucose (FPG), followed by an oral glucose tolerance test (OGTT) in those with FPG 6.1-6.9 mmol/L. Glycated haemoglobin A1c (HbA1c) has robust stability at ambient temperature, and can be performed on non-fasted capillary blood samples, making it an attractive potential alternative for screening. However, limitations of HbA1c include differential performance in different races, and its performance as a screening test has not been well characterized in Asian populations. This study compares HbA1c and FPG as diabetes screening modalities in 3540 community-dwelling Singapore residents of Chinese, Malay and Indian race to detect diabetes mellitus diagnosed based on blood glucose (FPG ≥ 7.0 mmol/L, 2 hr OGTT ≥ 11.1 mmol/L). The area under the receiver-operating-characteristic curve (AUC) was higher for FPG compared to HbA1c in the overall population and age, race and age-race strata, but these differences were not statistically significant. HbA1c > = 7.0% identified 95% of individuals with diabetes mellitus, and the remainder had impaired glucose tolerance (IGT). HbA1c cut-off at 6.1% had better sensitivity (0.825) to FPG at 6.1 mmol/L. The positive predictive value of HbA1c at 6.1% was 40-50% in different age-race combinations with a negative predictive value of about 98%. If follow-up screening with FPG is used, a lower cut-off at 5.6 mmol/L is appropriate in identifying people with pre-diabetes, as about 85% of people with HbA1c 6.1-6.9% and FPG 5.6-6.9 mmol/L had IFG/IGT or diabetes in the study sample. HbA1c is an appropriate alternative to FPG as a first-step screening test, and the combination of Hba1c > = 6.1% and FPG > = 5.6 mmol/L would improve the identification of individuals with diabetes mellitus and prediabetes.

Optimal Glycated Hemoglobin Cutoff Point for Diagnosis of Type 2 Diabetes in Iranian Adults

OBJECTIVES

The aim of this study was to evaluate the capability of glycated hemoglobin (A1C) levels to be a tool for identifying Iranian adults with diabetes and prediabetes.

METHODS

In a cross-sectional population-based study, 1,813 adults, men and women 35 to 75 years of age and without a history of diabetes and hemoglobinopathies, were included. Fasting blood glucose and A1C levels were obtained. According to the criteria of the American Diabetes Association, participants were categorized into 3 groups: newly diagnosed diabetes, prediabetes and healthy subjects. The optimal cutoff point for A1C in diabetes and prediabetes diagnosis was determined by studying the sensitivity and specificity of different cutoff points for A1C, while using different levels of fasting blood glucose as the gold standard.

RESULTS

Participants with newly diagnosed diabetes were significantly older than subjects with prediabetes and healthy subjects (mean [± SD] 47.3±12.9, 44.6±13.0 and 39.2±14.1 years, respectively) and also had higher body mass indexes. As expected, the levels of fasting blood glucose (8.79±2.24, 6.01±0.38 and 4.97±0.4 mmol/L) and A1C (6.55±1.4%, 5.61±0.61% and 5.28±0.59%) were significantly different in the groups (p<0.001). The optimal cutoff point for A1C to predict prediabetes was 5.5% (sensitivity of 60.5% and specificity of 63.1%) and for diabetes was 5.9% (sensitivity of 66.7% and specificity of 81.2%). ADA cutoff points for prediabetes and diabetes detection yielded a sensitivity of 45.2% and 39.8%, respectively.

CONCLUSIONS

The findings suggest the necessity of determining the A1C cutoffs for detecting diabetes or prediabetes in each region's population. They also suggest that the combination of these A1C cutoffs with fasting blood glucose levels are required to determine diabetes and prediabetes more accurately.

Genetics of HbA1c: a case study in clinical translation

Glycated hemoglobin (HbA1c) measures the amount of glucose in the blood in the previous 2-3 months and is used to test whether an individual has diabetes (HbA1c≥6.5%), or how well they are managing their diabetes. Genome-wide association studies have successfully identified multiple genomic loci influencing HbA1c, through both glycemic (factors that affect the amount blood glucose levels) and erythrocytic (factors that affect the red blood cell) pathways. Inaccuracies in HbA1c, due to non-glycemic variants, could lead to suboptimal care or adverse health consequences. A recently published example is the erythrocytic variant (rs1050828) in G6PD, which leads to the artificial lowering of HbA1c and missed diagnosis of diabetes using current thresholds. In this review we will discuss recent insights into the genetic etiology of HbA1c, and how these can translate to the clinic.

Glycaemic responses in Asian and non-Asian people with type 2 diabetes initiating insulin glargine 100 units/mL: A patient-level pooled analysis of 16 randomised controlled trials

AIMS

To compare outcomes between Asian and non-Asian patients with type 2 diabetes (T2D) inadequately controlled on oral antidiabetic drugs (OADs) initiating insulin glargine 100 units (U)/mL (Gla-100) in randomised controlled clinical trials.

METHODS

Post hoc analysis of patient-level data (Asian n = 235; non-Asian n = 3351) from 16 trials.

RESULTS

At baseline, Asian patients were younger with lower body mass index (BMI), fasting C-peptide, and fasting plasma glucose (FPG) than non-Asian patients (all P < .001). Asian patients had a higher mean glycosylated haemoglobin (HbA1c) at Week 24 and less reduction in HbA1c from baseline (7.4% vs. 7.2%; -1.3% vs. -1.6%, respectively; P = .0001), and were less likely to achieve HbA1c <7.0% (40% vs. 47%; P = .002) than non-Asian patients. Reductions in FPG and rates of hypoglycaemia were similar between Asian and non-Asian patients. Asian patients had less weight gain than non-Asian patients (+1.3 vs. +1.9 kg, respectively, P = .013).

CONCLUSIONS

In our post hoc meta-analysis, Gla-100 effectively lowers HbA1c and FPG in Asian patients with T2D uncontrolled on OADs with similar incidence of hypoglycaemia and less absolute weight gain compared with non-Asian patients. At a similar FPG reduction, fewer Asian patients achieved HbA1c target <7.0%, suggesting that prandial glucose needs to be addressed.

Impact of common genetic determinants of Hemoglobin A1c on type 2 diabetes risk and diagnosis in ancestrally diverse populations: A transethnic genome-wide meta-analysis

BACKGROUND

Glycated hemoglobin (HbA1c) is used to diagnose type 2 diabetes (T2D) and assess glycemic control in patients with diabetes. Previous genome-wide association studies (GWAS) have identified 18 HbA1c-associated genetic variants. These variants proved to be classifiable by their likely biological action as erythrocytic (also associated with erythrocyte traits) or glycemic (associated with other glucose-related traits). In this study, we tested the hypotheses that, in a very large scale GWAS, we would identify more genetic variants associated with HbA1c and that HbA1c variants implicated in erythrocytic biology would affect the diagnostic accuracy of HbA1c. We therefore expanded the number of HbA1c-associated loci and tested the effect of genetic risk-scores comprised of erythrocytic or glycemic variants on incident diabetes prediction and on prevalent diabetes screening performance. Throughout this multiancestry study, we kept a focus on interancestry differences in HbA1c genetics performance that might influence race-ancestry differences in health outcomes.

METHODS & FINDINGS

Using genome-wide association meta-analyses in up to 159,940 individuals from 82 cohorts of European, African, East Asian, and South Asian ancestry, we identified 60 common genetic variants associated with HbA1c. We classified variants as implicated in glycemic, erythrocytic, or unclassified biology and tested whether additive genetic scores of erythrocytic variants (GS-E) or glycemic variants (GS-G) were associated with higher T2D incidence in multiethnic longitudinal cohorts (N = 33,241). Nineteen glycemic and 22 erythrocytic variants were associated with HbA1c at genome-wide significance. GS-G was associated with higher T2D risk (incidence OR = 1.05, 95% CI 1.04-1.06, per HbA1c-raising allele, p = 3 × 10-29); whereas GS-E was not (OR = 1.00, 95% CI 0.99-1.01, p = 0.60). In Europeans and Asians, erythrocytic variants in aggregate had only modest effects on the diagnostic accuracy of HbA1c. Yet, in African Americans, the X-linked G6PD G202A variant (T-allele frequency 11%) was associated with an absolute decrease in HbA1c of 0.81%-units (95% CI 0.66-0.96) per allele in hemizygous men, and 0.68%-units (95% CI 0.38-0.97) in homozygous women. The G6PD variant may cause approximately 2% (N = 0.65 million, 95% CI 0.55-0.74) of African American adults with T2D to remain undiagnosed when screened with HbA1c. Limitations include the smaller sample sizes for non-European ancestries and the inability to classify approximately one-third of the variants. Further studies in large multiethnic cohorts with HbA1c, glycemic, and erythrocytic traits are required to better determine the biological action of the unclassified variants.

CONCLUSIONS

As G6PD deficiency can be clinically silent until illness strikes, we recommend investigation of the possible benefits of screening for the G6PD genotype along with using HbA1c to diagnose T2D in populations of African ancestry or groups where G6PD deficiency is common. Screening with direct glucose measurements, or genetically-informed HbA1c diagnostic thresholds in people with G6PD deficiency, may be required to avoid missed or delayed diagnoses.

Impact of demographics and disease progression on the relationship between glucose and HbA1c

CONTEXT

Several studies have shown that the relationship between mean plasma glucose (MPG) and glycated haemoglobin (HbA1c) may vary across populations. Especially race has previously been referred to shift the regression line that links MPG to HbA1c at steady-state (Herman & Cohen, 2012).

OBJECTIVE

To assess the influence of demographic and disease progression-related covariates on the intercept of the estimated linear MPG-HbA1c relationship in a longitudinal model.

DATA

Longitudinal patient-level data from 16 late-phase trials in type 2 diabetes with a total of 8927 subjects was used to study covariates for the relationship between MPG and HbA1c. The analysed covariates included age group, BMI, gender, race, diabetes duration, and pre-trial treatment. Differences between trials were taken into account by estimating a trial-to-trial variability component.

PARTICIPANTS

Participants included 47% females and 20% above 65years. 77% were Caucasian, 9% were Asian, 5% were Black and the remaining 9% were analysed together as other races.

ANALYSIS

Estimates of the change in the intercept of the MPG-HbA1c relationship due to the mentioned covariates were determined using a longitudinal model.

RESULTS

The analysis showed that pre-trial treatment with insulin had the most pronounced impact associated with a 0.34% higher HbA1c at a given MPG. However, race, diabetes duration and age group also had an impact on the MPG-HbA1c relationship.

CONCLUSION

Our analysis shows that the relationship between MPG and HbA1c is relatively insensitive to covariates, but shows small variations across populations, which may be relevant to take into account when predicting HbA1c response based on MPG measurements in clinical trials.

Adiposity rebound from three to six years of age was associated with a higher insulin resistance risk at eight-and-a-half years in a birth cohort study

AIM

The association between adiposity rebound and insulin resistance in middle childhood has seldom been studied. We examined the effect of body mass index (BMI) velocity and early adiposity rebound on the insulin resistance of prepubertal children.

METHODS

BMI data from a longitudinal follow-up of a birth cohort in Thailand were used. The homoeostatic model assessment of insulin resistance (HOMA-IR) was calculated from 12-hour fasting plasma glucose and serum insulin at eight-and-a-half years of age. BMI velocity was calculated from four periods: zero to one, one to three, three to six and six to eight-and-a-half years of age. A multiple linear regression model was used to assess the association of BMI velocity during these four periods and insulin resistance at the age of eight-and-a-half years.

RESULTS

In 814 children - 76.7% of the initial cohort - BMI velocities between years one to three, three to six and six to eight-and-a-half years were positively associated with HOMA-IR levels after adjusting for demographic, behavioural and socio-economic factors. Children who had BMI gains between three and six years had mean HOMA-IR values that were 43% higher than those who did not.

CONCLUSION

BMI velocity during early and middle childhood, and early adiposity rebound between three and six years, was associated with a higher insulin resistance risk at eight-and-a-half years.

High Prevalence of Diabetes and Prediabetes and Their Coexistence with Cardiovascular Risk Factors in a Hispanic Community

This study examined the prevalence and association of diabetes mellitus (DM) and prediabetes with cardiovascular risk factors among Puerto Ricans adults. Data from a household survey of 857 adults aged 21-79 years who underwent interviews, physical exams, and blood draws were analyzed. Prevalence of total DM and prediabetes was estimated using American Diabetes Association diagnostic criteria of fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c). Poisson regression models were used to estimate the prevalence ratio for each cardiovascular risk factor under study. Age-standardized prevalence of total DM and prediabetes, detected by FPG and/or HbA1c, was 25.5 and 47.4 %, respectively. Compared with participants with normoglycemia, those with previously diagnosed DM, undiagnosed DM, and prediabetes had more adverse cardiovascular risk factor profiles, characterized by a higher prevalence of general and abdominal obesity, hypertension, low HDL cholesterol, elevated LDL cholesterol, elevated triglycerides, and elevated plasminogen activator inhibitor 1 (p < 0.05). The high prevalence of DM and prediabetes calls for public health actions to plan and implement lifestyle interventions to prevent or delay the onset of DM and cardiovascular disease.

Prevalence of dysglycaemia in rural Andhra Pradesh: 2005, 2010, and 2014

BACKGROUND

Communities in rural Andhra Pradesh may be at increasing risk of diabetes. In the present study we analyzed three cross-sectional studies over 9 years to estimate the changing prevalence of dysglycemia (diabetes and prediabetes).

METHODS

The 2005 study sampled 4535 individuals from 20 villages, the 2010 study sampled 4024 individuals from 14 villages, and the 2014 project of 62 254 individuals sought to include all adults aged 40-85 years from 54 villages. Blood glucose levels were estimated using a hand-held device in 2005 and 2014 and using HbA1c dried blood spots in 2010.

RESULTS

In primary analyses restricted to assays based on fasting samples (2005, n = 3243; 2014, n = 749), the prevalence estimates for dysglycemia were 53.7% (95% confidence interval [CI] 51.8%-55.7%) in 2005 and 62.0% (95% CI 58.5%-65.4%) in 2014 (P < 0.001). Over the same period, mean body mass index (BMI) increased from 22.2 to 24.3 kg/m² (mean difference 2.1 kg/m² ; 95% CI 2.0-2.2 kg/m² ; P < 0.001). In secondary analyses using data from all participants (2005, n = 4535; 2010, n = 4024; 2014, n = 62 254), regardless of measurement technique, the estimated prevalence of dysglycemia was 53.9% (95% CI 52.0%-55.9%) in 2005, 50.5% (95% CI 46.1%-54.9%) in 2010, and 41.3% (95% CI 40.9%-41.7%) in 2014 (P < 0.001).

CONCLUSIONS

The prevalence of dysglycemia was high at every assessment using every measurement method. Dysglycemia in this population is most likely to have risen with the rise in BMI. The decline in prevalence suggested by the secondary analyses was likely due to confounding from the different assessment methods.

Ideal glycated hemoglobin cut-off points for screening diabetes and prediabetes in a Chinese population

AIMS/INTRODUCTION

The aims of the present study were to evaluate the diagnostic value of fasting plasma glucose, 2-h postload plasma glucose and glycosylated hemoglobin (HbA1c) measurements in the screening of diabetes and prediabetes, and to determine the cut-off point of HbA1c in the diagnosis of diabetes and prediabetes in a Chinese population.

MATERIALS AND METHODS

A total of 7,611 individuals aged 40 years or older, who did not have a prior history of diabetes, were randomly selected in the Changchun area. For each participant, a questionnaire was completed, and a physical examination and an oral glucose tolerance test were carried out. The values of fasting plasma glucose, 2-h postload plasma glucose and HbA1c were compared by area under the receiver operating characteristic curves. The Youden index was used to identify the optimal cut-off point of HbA1c in the diagnosis of diabetes and prediabetes.

RESULTS

The prevalence of newly diagnosed diabetes and prediabetes was 12.71% and 29.39%, respectively. In participants with newly diagnosed diabetes, the area under the receiver operating characteristic curve was 0.8368 for fasting plasma glucose, 0.9330 for 2-h postload plasma glucose and 0.8064 for HbA1c; whereas for prediabetes, these values were 0.8022, 0.9288 and 0.6895, respectively. In addition, an HbA1c threshold of 6.3% showed the highest Youden index (0.4799) for detecting diabetes; furthermore, an HbA1c threshold of 5.8% showed the highest Youden index (0.2866) for detecting prediabetes.

CONCLUSIONS

HbA1c ≥6.3% (45 mmol/mol) and between 5.8% and 6.2% (40-44 mmol/mol) were the optimal cut-off values for the diagnosis of diabetes and prediabetes, respectively, in a Chinese population.

Diabetes case finding in the emergency department, using HbA1c: an opportunity to improve diabetes detection, prevention, and care

OBJECTIVE

We assessed the efficacy of routine glycated hemoglobin (HbA1c) testing to detect undiagnosed diabetes and prediabetes in an urban Australian public hospital emergency department (ED) located in an area of high diabetes prevalence.

METHODS

Over 6 weeks, all patients undergoing blood sampling in the ED had their random blood glucose measured. If ≥5.5 mmol/L (99 mg/dL), HbA1c was measured on the same sample. HbA1c levels ≥6.5% (48 mmol/mol) and 5.7-6.4% (39-46 mmol/mol) were diagnostic of diabetes and prediabetes, respectively. Hospital records were reviewed to identify patients with previously diagnosed diabetes.

RESULTS

Among 4580 presentations, 2652 had blood sampled of which 1267 samples had HbA1c measured. Of these, 487 (38.4%) had diabetes (either HbA1c≥6.5% or a prior diagnosis), and a further 347 (27.4%) had prediabetes. Among those with diabetes, 32.2% were previously undiagnosed.

CONCLUSIONS

Routine HbA1c testing in the ED identifies a large number of people with undiagnosed diabetes and prediabetes, and provides an opportunity to improve their care.

Can HbA1c replace OGTT for the diagnosis of diabetes mellitus among Chinese patients with impaired fasting glucose?

BACKGROUND

HbA1c ≥ 6.5% has been recommended as a diagnostic criterion for the detection of diabetes mellitus (DM) since 2010 because of its convenience, stability and significant correlation with diabetic complications. Nevertheless, the accuracy of HbA1c compared to glucose-based diagnostic criteria varies among subjects of different ethnicity and risk profile.

OBJECTIVES

This study aimed to evaluate the accuracy of HbA1c for diagnosing DM compared to the diagnosis by oral glucose tolerance test (OGTT) and the optimal HbA1c level to diagnose DM in primary care Chinese patients with impaired fasting glucose (IFG).

METHODS

A cross-sectional study was carried out in three public primary care clinics in Hong Kong. About 1128 Chinese adults with IFG (i.e. FG level between 5.6 and 6.9 mmol/l in the past 18 months) were recruited to receive paired OGTT and HbA1c tests. Sensitivities and specificities of HbA1c at different threshold levels for predicting DM compared to the diagnosis by OGTT were evaluated. A receiver operating characteristic (ROC) curve was used to determine the optimal cut-off level.

RESULTS

Among the 1128 subjects (mean age 64.2±8.9 year, 48.8% male), 229 (20.3%) were diagnosed to have DM by OGTT. The sensitivity and specificity of HbA1c ≥6.5% were 33.2% and 93.5%, respectively, for predicting DM diagnosed by OGTT. The area under the ROC curve was 0.770, indicating HbA1c had fair discriminatory power. The optimal cut-off threshold of HbA1c was 6.3% for discriminating DM from non-DM, with sensitivity and specificity of 56.3% and 85.5%, respectively. HbA1c ≥ 5.6% has the highest sensitivity and negative predictive value of 96.1% and 94.5%, respectively.

CONCLUSIONS

HbA1c ≥ 6.5% is highly specific in identifying people with DM, but it may miss the majority (66.8%) of the DM cases. An HbA1c threshold of <5.6% is more appropriate to be used for the exclusion of DM. OGTT should be performed for the confirmation of DM among Chinese patients with IFG who have an HbA1c between 5.6% and 6.4%.

Glycated hemoglobin and incident type 2 diabetes in singaporean chinese adults: the Singapore Chinese health study

Background

The American Diabetes Association recently included glycated hemoglobin in the diagnostic criteria for diabetes, but research on the utility of this biomarker in Southeast Asians is scant. The aim of this study was to evaluate the association between percent HbA1c and incident diabetes in an Asian population of adult men and women without reported diabetes.

Methods

Data analysis of 5,770 men and women enrolled in the Singapore Chinese Health Study who provided a blood sample at the follow-up I visit (1999–2004) and had no cancer and no reported history of diabetes or cardiovascular disease events. Diabetes was defined as self-report of physician diagnosis, identified at the follow-up II visit (2006–2010).

Results

Hazard ratios (and 95% confidence intervals) for incident diabetes by 5 categories of HbA1c were estimated with Cox regression models and continuous HbA1c with cubic spline analysis. Compared to individuals with an HbA1c ≤ 5.7% (≤39 mmol/mol), individuals with HbA1c 5.8–5.9% (40–41 mmol/mol), 6.0–6.1% (42–43 mmol/mol), 6.2–6.4% (44–47 mmol/mol), and ≥ 6.5% (≥48 mmol/mol) had significantly increased risk for incident diabetes during follow-up. In cubic spline analysis, levels below 5.7% HbA1c were not significantly associated with incident diabetes.

Conclusions

Our study found a strong and graded association with HbA1c 5.8% and above with incident diabetes in Chinese men and women.

Prediabetes: The Variation between HbA1c and Fasting Plasma Glucose

PURPOSE

The prevalence of Diabetes Type 2 is on the rise internationally. Currently, Fasting Plasma Glucose (FPG) and HbA1c are both used to determine if an individual is diabetic or prediabetic. We aimed to describe the prevalence of diabetes, prediabetes, and glycemic control in a population-based sample of elderly Hispanic and non-Hispanic White participants in New Mexico.

METHODS

To do this, we compared HbA1c with FPG using Chi-Square analysis across gender and ethnicity to provide information for future health care policy. We also performed non-parametric regression using a locally weighted smoothing technique to investigate the relationship between FPG and HbA1c levels.

RESULTS

Our analysis identifies a large variation between the sensitivity of HbA1c and FPG in the identification of both prediabetes and diabetes. Interestingly, 95% of diabetics defined by FPG are also defined by HbA1c, representing overlap between the two measures. When comparing the prevalence of prediabetes between the two measures, the overlap of FPG with HbA1c was only 30% and HbA1c identifies more individuals as prediabetic than FPG. Prevalence of diabetes was also higher when defined by HbA1c compared to FPG and the overall agreement between HbA1c and FPG appears to be poor particularly by sex and ethnicity (K=0.22-0.34). Glycemic control was poor overall with Hispanics displaying a larger amount of uncontrolled diabetes.

CONCLUSION

We compared HbA1c and FPG by gender and ethnicity and showed both measures of diabetes differ in their sensitivity across ethnic groups. Our results suggest that using HbA1c, rather than FPG, results in higher rates of prediabetes and diabetes, a finding with numerous implications for health care practice.

Tracking of metabolic control from childhood to young adulthood in type 1 diabetes

OBJECTIVE

This prospective longitudinal survey was designed to follow patients with diabetes from disease onset in childhood over an extended period of time including puberty until young adulthood with respect to metabolic control.

STUDY DESIGN

An electronic diabetes patient documentation system used in diabetes centers in Austria and Germany was utilized for standardized data collection. Complete documentation of metabolic control for prepuberty (≤ 13 years), puberty (14-19 years), and adulthood (≥ 20 years) was available in 1146 patients.

RESULTS

Median age at diabetes manifestation was 7.2 (IQR 4.7-9.4) years; 49% were male. In the prepubertal stage, median glycated hemoglobin A1c (HbA1c) was 7.5 (IQR 6.8-8.3), during puberty 8.0 (IQR 7.3-8.9), and after puberty 7.8 (IQR 7.1-9.0). A significant intra-individual correlation was found for prepuberty to puberty HbA1c levels (R = 0.55, P < .001), puberty to adulthood (R = 0.59, P < .001), as well as prepuberty to adulthood (R = 0.30, P < .001). When patients were divided into tertiles of prepubertal HbA1c, HbA1c increased in all 3 groups over time, however, significant group differences tracked into adulthood (P < .001 at all stages). A regression model identified pre-pubertal HbA1c as a significant and relevant predictor of metabolic control in young adulthood adjusted for confounders (P < .001).

CONCLUSIONS

This survey provides evidence for long-term tracking of metabolic control from childhood until adulthood, suggesting an early focus on metabolic control.

The relationship between fasting plasma glucose and HbA1c during intensive periods of glucose control in antidiabetic therapy

OBJECTIVE

HbA1c measurements are typically less variable than fasting plasma glucose (FPG) for diagnosing diabetes, and for assessment of progress on glucose control therapy. However HbA1c reaches steady-state relative to average plasma glucose over about 120 days. HbA1c thus overestimates average FPG during first three months of starting therapy in newly diagnosed diabetic patients, and care needs to be exercised in interpreting HbA1c measurements during this period. At steady-state excellent regression exists between HbA1c and FPG. We hypothesize that this regression can also be used to obtain reliable estimates of HbA1c relative to FPG at 4 and 8 weeks following the onset of therapy.

MATERIALS AND METHODS

We collected FPG and HbA1c data of type 2 diabetic patients over the first 8 weeks of starting antidiabetic treatment. We fit linear and nonlinear regression models to steady-state data, and estimated how much measured HbA1c deviates at 4 and 8 weeks from these theoretical relations.

RESULTS

If measured HbA1c is decremented by 0.7% (8 mmol/mol) at 4 weeks and 0.3% (3 mmol/mol) at 8 weeks, this corrected HbA1c is a better predictor of the corresponding FPG. Using hyperbolic regression, corrections to HbA1c are 0.5 and 0.1% (5 and 1 mmol/mol), respectively.

CONCLUSION

With the corrections proposed here, HbA1c measurements can be better interpreted in the early weeks of antidiabetic treatment.