HbA1c of 6.5% to diagnose diabetes mellitus -- does it work for us? -- the Bellville South Africa study

Discovering hidden patterns: Association rules for cardiovascular diseases in type 2 diabetes mellitus

BACKGROUND

It is increasingly common to find patients affected by a combination of type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD), and studies are able to correlate their relationships with available biological and clinical evidence. The aim of the current study was to apply association rule mining (ARM) to discover whether there are consistent patterns of clinical features relevant to these diseases. ARM leverages clinical and laboratory data to the meaningful patterns for diabetic CAD by harnessing the power help of data-driven algorithms to optimise the decision-making in patient care.

AIM

To reinforce the evidence of the T2DM-CAD interplay and demonstrate the ability of ARM to provide new insights into multivariate pattern discovery.

METHODS

This cross-sectional study was conducted at the Department of Biochemistry in a specialized tertiary care centre in Delhi, involving a total of 300 consented subjects categorized into three groups: CAD with diabetes, CAD without diabetes, and healthy controls, with 100 subjects in each group. The participants were enrolled from the Cardiology IPD & OPD for the sample collection. The study employed ARM technique to extract the meaningful patterns and relationships from the clinical data with its original value.

RESULTS

The clinical dataset comprised 35 attributes from enrolled subjects. The analysis produced rules with a maximum branching factor of 4 and a rule length of 5, necessitating a 1% probability increase for enhancement. Prominent patterns emerged, highlighting strong links between health indicators and diabetes likelihood, particularly elevated HbA1C and random blood sugar levels. The ARM technique identified individuals with a random blood sugar level > 175 and HbA1C > 6.6 are likely in the "CAD-with-diabetes" group, offering valuable insights into health indicators and influencing factors on disease outcomes.

CONCLUSION

The application of this method holds promise for healthcare practitioners to offer valuable insights for enhancing patient treatment targeting specific subtypes of CAD with diabetes. Implying artificial intelligence techniques with medical data, we have shown the potential for personalized healthcare and the development of user-friendly applications aimed at improving cardiovascular health outcomes for this high-risk population to optimise the decision-making in patient care.

Diagnostic cut-off value of haemoglobin A1c for diabetes mellitus in Harare, Zimbabwe

Very little is known about the diagnostic performance of the American Diabetes Association glycated haemoglobin (HbA1c) cut-off of 6.5% in resource-limited settings. This study, conducted between February 2023 and May 2023, aimed to determine the optimal HbA1c cut-off for the diagnosis of diabetes mellitus by measuring HbA1c and fasting plasma glucose levels in 120 adults attending care at a tertiary hospital in Harare, Zimbabwe. The optimal HbA1c cut-off was 6.1% and glucose levels were strongly correlated with HbA1c values. The prevalence of diabetes mellitus was higher (28.3%) at our derived HbA1c cut-off than with the American Diabetes Association criterion (21.6%).

What this study adds

This study highlights the need for population-specific cut-off HbA1c values in the diagnosis of diabetes mellitus.

Identifying sex-specific anthropometric measures and thresholds for dysglycemia screening in an HIV-endemic rural South African population

Valid screening and diagnostic algorithms are needed to achieve 2030 targets proposed by the WHO's Global Diabetes Compact. We explored anthropometric thresholds to optimally screen and refer individuals for diabetes testing in rural South Africa. We evaluated screening thresholds for waist circumference (WC), body mass index (BMI), and waist-hip ratio (WHR) to detect dysglycemia based on a glycated hemoglobin (HbA1C) ≥6.5% among adults in a population-based study in South Africa using weighted, non-parametric ROC regression analyses. We then assessed the diagnostic validity of traditional obesity thresholds, explored optimal thresholds for this population, and fit models stratified by sex, age, and HIV status. The prevalence of dysglycemia in the total study population (n = 17,846) was 7.7%. WC had greater discriminatory capacity than WHR to detect dysglycemia in men (p-value<0.001) and women (p<0.001). WC had greater discriminatory capacity than BMI to detect dysglycemia in women (p<0.001). However, BMI and WC performed similarly for men (p = 0.589). Whereas traditional WC thresholds for women (>81cm) performed well (sensitivity 91%, positive predictive value [PPV] 14.9%), substantially lower thresholds were needed to achieve acceptable sensitivity and PPV among men (traditional >94cm, derived >79.5cm). WC outperforms BMI as an anthropometric screening measure for dysglycemia in rural South Africa. Whereas WC guideline thresholds are appropriate for women, male-derived WC cutoffs performed better at lower thresholds. In this rural South African population, thresholds that maximize specificity and PPV for efficient resource allocation may be preferred.

Type 2 diabetes mellitus and coronary artery stenosis: a risk pattern association study

Aim: Cardiovascular diseases (CVD) are the leading cause of death globally. In the condition of type 2 diabetes mellitus (T2DM), the prevalence of CVD increase parallel with the rise of metabolic complication and higher incidence of coronary artery stenosis. The aim of this study was to compare the level of percent stenosis in coronary arteries in patients with coronary artery disease (CAD) with and without T2DM, and to measure the severity of CVD using Gensini score (GS) through angiographic data. Methods: The current study was conducted in tertiary care specialized hospital in Delhi, India. The level of percent stenosis in coronary arteries was compared in patients with CAD with and without T2DM. The patients were divided into two groups: group I included 100 patients with T2DM, and group II included 100 non-diabetic CAD patients who underwent coronary angiography by Judkin’s technique. The severity of CVD was measured by GS through angiographic data. The serum levels of glycated haemoglobin (HbA1c) ≥ 6.5% were considered diabetic. Results: Significant difference was observed in serum HbA1c, and random blood sugar levels between group I and group II were also observed (P ≤ 0.001). Serum HbA1c shows a significant positive association with GS (r = 0.36, P = 0.007). Conclusions: The study shows a significant level of stenosis in coronary arteries of CAD diabetic patients. However, further prospective analysis of a larger population size will be needed to strengthen the findings and the significant association.

Early postpartum HbA1c after hyperglycemia first detected in pregnancy-Imperfect but not without value

BACKGROUND

South African women of childbearing age are disproportionally affected by obesity and at significant risk of Type 2 Diabetes Mellitus (T2DM). Unless pregnant, they do not readily undergo screening for T2DM. With a local focus on improved antenatal care, hyperglycemia is often first detected in pregnancy (HFDP). This may erroneously be attributed to Gestational Diabetes Mellitus (GDM) in all without considering T2DM. Glucose evaluation following pregnancy is essential for early detection and management of women with T2DM in whom persistent hyperglycemia is to be expected. Conventional testing with an oral glucose tolerance test (OGTT) is cumbersome, prompting investigation for alternate solutions.

AIM

To compare the diagnostic performance of HbA1c to the current gold standard OGTT in women with HFDP 4-12 weeks post-delivery.

METHODS

Glucose homeostasis was assessed with OGTT and HbA1c in 167 women with HFDP, 4-12 weeks after delivery. Glucose status was based on American Diabetes Association criteria.

RESULTS

Glucose homeostasis was assessed at 10 weeks (IQR 7-12) after delivery. Of the 167 participants, 52 (31%) had hyperglycemia, which was comprised of 34 (20%) prediabetes and 18 (11%) T2DM. Twelve women in the prediabetes subgroup had diagnostic fasting plasma glucose (FPG) and 2-hour plasma glucose (2hPG), but in two-thirds of the patients (22/34) only one time point proved diagnostic. The FPGs and the 2hPGs of six women with HbA1c-based T2DM were both within the prediabetes diagnostic range. According to the HbA1c measurements, 85% of 52 participants with gold standard OGTT defined hyperglycemia (prediabetes and T2DM) as well as 15 of 18 women with postpartum persistent T2DM were correctly classified. According to FPG, 15 women with persistent hyperglycemia would have been missed (11 with prediabetes and four with T2DM; 29%). When compared to an OGTT, a single HbA1c of 6.5% (48mmol/mol) postpartum demonstrated a sensitivity of 83% and specificity of 97% for the identification of T2DM.

CONCLUSION

HbA1c may improve access to postpartum testing in overburdened clinical settings where the required standards of OGTT cannot be guaranteed. HbA1c is a valuable test to detect women who will benefit most from early intervention but cannot unequivocally replace OGTT.

Glycated haemoglobin and fasting plasma glucose tests in the screening of outpatients for diabetes and abnormal glucose regulation in Uganda: A diagnostic accuracy study

BACKGROUND AND OBJECTIVES

To understand the utility of glycated haemoglobin (HBA1C) in screening for diabetes and Abnormal Glucose Regulation (AGR) in primary care, we compared its performance to that of the fasting plasma glucose (FPG) test.

METHODS

This was a prospective diagnostic accuracy study conducted in eastern Uganda. Patients eligible for inclusion were consecutive adults, 30-75 years, receiving care at the outpatient department of a general hospital in eastern Uganda. We determined the sensitivity, specificity and optimum cut-off points for HBA1C and FPG tests using the oral glucose tolerance test (OGTT) as a clinical reference standard.

RESULTS

A total of 1659 participants underwent FPG testing of whom 310 were also HBA1C and OGTT tested. A total of 113 tested positive for diabetes and 168 for AGR on the OGTT. At recommended cut-off points for diabetes, the HBA1C and FPG tests had comparable sensitivity [69.8% (95% CI 46.3-86.1) versus 62.6% (95% CI 41.5-79.8), respectively] and specificity [98.6% (95% CI 95.4-99.6) versus 99.4% (95% CI 98.9-99.7), respectively]. Similarly, the sensitivity of HBA1C and the FPG tests for Abnormal Glucose Regulation (AGR) at ADA cut-offs were comparable [58.9% (95% CI 46.7-70.2) vs 47.7% (95% CI 37.3-58.4), respectively]; however, the HBA1C test had lower specificity [70.7% (95% CI 65.1-75.8)] than the FPG test [93.5% (95% CI 88.6-96.4)]. At the optimum cut-offs points for diabetes [45.0 mmol/mol (6.3%) for HBA1C and 6.4 mmol/L (115.2 mg/dl) for FPG], HBA1C and FPG sensitivity [71.2% (95% CI 46.9-87.8) versus 72.7% (95% CI 49.5-87.8), respectively] and specificity [95.1% (95% CI91.8 97.2) versus 98.7% (95% CI 98.0 99.2), respectively] were comparable. Similarly, at the optimum cut-off points for AGR [42.0 mmol/mol (6.0%) for the HBA1C and 5.5 mmol/l (99.0 mg/dl) for the FPG test], HBA1C and FPG sensitivity [42.3% (95% CI 31.8-53.6) and 53.2 (95% CI 43.1-63.1), respectively] and specificity [89.1% (95% CI 84.1 92.7) and 92.7% (95% CI 91.0 94.1), respectively] were comparable.

DISCUSSION

HBA1C is a viable alternative diabetes screening and confirmatory test to the FPG test; however, the utility of both tests in screening for prediabetes in this outpatient population is limited.

Combining HbA1c and glycated albumin improves detection of dysglycaemia in mixed-ancestry South Africans

BACKGROUND

Combining HbA_1c with glycated albumin (GA) may improve detection of dysglycaemia. As BMI correlates positively with HbA_1c and negatively with GA, HbA_1c may be more effective in obese and GA in nonobese individuals.

METHODS

To relate these findings to Africans, we assessed in 1274 South Africans living in CapeTown (male 26%; age 48±16y; BMI 28.7 kg/m² (range 15.6-73.8); obesity 39.9% and no prior diabetes history) the: (1) correlation of BMI with HbA_1c and GA, (2) ability of HbA_1c and GA separately and jointly, to detect OGTT-diagnosed dysglycaemia (diabetes plus prediabetes). Data collection took place between 2014 and 2016 in the City of Cape Town. Dysglycaemia was diagnosed by glucose criteria for the OGTT. Youden index was used to optimize diagnostic thresholds for HbA_1c and GA.

FINDINGS

Normal glucose tolerance, prediabetes and diabetes occurred in 76%, 17% and 7%, respectively. BMI positively correlated with HbA_1c [r = 0·34 [95%CI: 0·29,0·39)] and negatively with GA [-0·08 (0·13,0·03)]. For HbA_1c the optimal threshold by Youden-index for dysglycaemia diagnosis was: 6·0% (95%CI: 5·8,6·2) and for GA: 13·44% (12·72,14·71). In the nonobese, obese and total cohort, HbA_1c-alone detected: 51% (42-60), 72% (65,78), 63% (57,68), respectively; GA-alone detected 55% (52% (46,63), 52% (44, 59) and 53% (47,53), respectively; whereas: HbA_1c+GA detected: 69% (60,76), 82% (75,87) and 76% (71, 81). Therefore, for the total cohort detection of dysglycaemia HbA_1c-alone vs HbA_1c+GA detected 63% (57,68) vs 76% (71,81).

INTERPRETATION

The opposite correlations of HbA_1c and GA with BMI have now been demonstrated in an African-based population. Improving detection of dysglycaemia by combining HbA_1c and GA has important implications for diabetes risk screening.

FUNDING

AES is supported by the intramural programs of the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of Minority Health and Health Disparities of the National Institutes of Health (NIH, Bethesda, Maryland, USA). DBS is supported by the intramural program of the Clinical Center of NIH. The South African Medical Research Council (SAMRC) funded the VMH study with funds from the National Treasury under its Economic Competitiveness and Support Package (MRC-RFA-UFSP-01-2013/VMH Study).

The diagnostic accuracy of HbA1c , compared to the oral glucose tolerance test, for screening for type 2 diabetes mellitus in Africa-A systematic review and meta-analysis

OBJECTIVE

To assess the diagnostic accuracy of glycated haemoglobin A_1c (HbA_1c ), compared to fasting plasma glucose (FPG) and the oral glucose tolerance test (OGTT), in screening for type 2 diabetes (T2D) in Africa.

METHODS

We systematically searched databases for studies that compared the HbA_1c to either the OGTT, or the FPG for T2D diagnosis were included. The QUADAS 2 tool was used for assessing the quality of included studies. We used the split component synthesis (SCS) method for the meta-analysis of diagnostic accuracy studies to pool the studies for meta-analysis of sensitivity and specificity, primarily at the HbA_1c ≥48 mmol/mol (6.5%) cut-off and at other cut-offs. We assessed heterogeneity using the I²  statistic and publication bias using Doi plots.

RESULTS

Eleven studies, from seven African countries, with 12,925 participants, were included. Against the OGTT, HbA_1c ≥48 mmol/mol (6.5%) had a pooled sensitivity of 57.7% (95% confidence interval [CI] 43.4-70.9) and specificity of 92.3% (95% CI 83.9-96.5). Against the FPG, HbA_1c ≥48 mmol/mol (6.5%) had a pooled sensitivity of 64.5% (95% CI 50.5-76.4) and specificity of 94.3% (95% CI 87.9-97.5). The highest sensitivity for HbA_1c , against the OGTT, was at the 42 mmol/mol (6.0%) cut-off.

CONCLUSION

In Africa, the HbA_1c ≥48 mmol/mol (6.5%) cut-off may miss almost half of the individuals with T2D based on blood glucose measures.

Diagnostic Accuracy of Point-of-Care Tests Measuring Glycosylated Haemoglobin (HbA1c) for Glycemic Control: A Field Study in India

Objectives This study was performed to estimate diagnostic accuracy of the two commercially available point-of-care tests to identify poor glycemic control defined by HbA1c levels, with high-performance liquid chromatography (HPLC) as a reference. Settings The study was carried at two locations, general medical outpatient department of a teaching medical college in Bhopal (urban), and a primary health care centre in a rural area in the state of Madhya Pradesh, India. Participants All individuals with diabetes mellitus who presented to the health care facility for assessment of glycemic control. We compared HbA1c estimated from two index tests (Hemocue Hb 501, Sweden; SD Biosensor, South Korea) from capillary blood samples with HPLC performed from venous blood, as a reference standard. Primary and secondary outcome measures Diagnostic properties of index tests such as sensitivity, specificity, positive and negative predictive value and diagnostic accuracy for identifying poor glycemic control were primary outcome measures. Lin's concordance correlation coefficient (CCC) was secondary outcome measure. Results Out of 114 patients, all received reference standard - 103 patients received Hemocue A1C test and 110 patients received SD Biosensor test. Overall both the index tests had similar diagnostic accuracy estimates. The area under the Receiver Operating Curve for SDA1c device was 0.935 (95% CI 0.886-0.983), and for Hemocue device was 0.938 (95% CI 0.893-0.984). The Hemocue device HbA1c value of above 7.0 (positive) correctly predicted poor glycemic control 92% times (81.58% for SD device). There were 4 vs. 11 device failures and 14 vs. 12 failures with SD and Hemocue, respectively. Ambient air temperatures were no different for the device test failures. Conclusions Commercially available point-of-care tests evaluated in this study are comparable and an acceptable alternative to HPLC-based measurements for the assessment of glycemic control. Tests and device failure rates of both the index tests are similar.

Concordance between fasting plasma glucose and HbA1c in the diagnosis of diabetes in black South African adults: a cross-sectional study

OBJECTIVES

We investigated concordance between haemoglobin A1c (HbA₁c)-defined diabetes and fasting plasma glucose (FPG)-defined diabetes in a black South African population with a high prevalence of obesity.

DESIGN

Cross-sectional study.

SETTING

Rural South African population-based cohort.

PARTICIPANTS

765 black individuals aged 40-70 years and with no history of diabetes.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was concordance between HbA_1c-defined diabetes and FPG-defined diabetes. Secondary outcome measures were differences in anthropometric characteristics, fat distribution and insulin resistance (measured using Homoeostatic Model Assessment of Insulin Resistance (HOMA-IR)) between those with concordant and discordant HbA_1c/FPG classifications and predictors of HbA_1c variance.

RESULTS

The prevalence of HbA_1c-defined diabetes was four times the prevalence of FPG-defined diabetes (17.5% vs 4.2%). Classification was discordant in 15.7% of participants, with 111 individuals (14.5%) having HbA_1c-only diabetes (kappa 0.23; 95% CI 0.14 to 0.31). Median body mass index, waist and hip circumference, waist-to-hip ratio, subcutaneous adipose tissue and HOMA-IR in participants with HbA_1c-only diabetes were similar to those in participants who were normoglycaemic by both biomarkers and significantly lower than in participants with diabetes by both biomarkers (p<0.05). HOMA-IR and fat distribution explained additional HbA_1c variance beyond glucose and age only in women.

CONCLUSIONS

Concordance was poor between HbA_1c and FPG in diagnosis of diabetes in black South Africans, and participants with HbA_1c-only diabetes phenotypically resembled normoglycaemic participants. Further work is necessary to determine which of these parameters better predicts diabetes-related morbidities in this population and whether a population-specific HbA_1c threshold is necessary.

Prevalence of Type 2 Diabetes in South Africa: A Systematic Review and Meta-Analysis

Synthesis of existing prevalence data using rigorous systematic review methods is considered an effective strategy to generate representative and robust prevalence figures to inform health planning and policy. The purpose of this systematic review was to identify, collate, and synthesise all studies reporting the prevalence of total and newly diagnosed type 2 diabetes (T2DM), impaired glucose tolerance (IGT), and impaired fasting glucose (IFG) in South Africa. Four databases, PubMed, Scopus, Web of Science, and African Index Medicus were searched for articles published between January 1997 and June 2020. A total of 1886 articles were identified, of which 11 were included in the meta-analysis. The pooled prevalence in individuals 25 years and older was 15.25% (11.07–19.95%) for T2DM, 9.59% (5.82–14.17%) for IGT, 3.55% (0.38–9.61%) for IFG, and 8.29% (4.97–12.34%) for newly diagnosed T2DM. Although our pooled estimate may be imprecise due to significant heterogeneity across studies with regard to population group, age, gender, setting, diagnostic test, and study design, we provide evidence that the burden of glucose intolerance in South Africa is high. These factors contribute to the paucity of representative T2DM prevalence data. There is a need for well-designed epidemiological studies that use best-practice and standardised methods to assess prevalence.

Poor cardiovascular health is associated with subclinical atherosclerosis in apparently healthy sub-Saharan African populations: an H3Africa AWI-Gen study

BACKGROUND

The cardiovascular health index (CVHI) introduced by the American Heart Association is a valid, accessible, simple, and translatable metric for monitoring cardiovascular health in a population. Components of the CVHI include the following seven cardiovascular risk factors (often captured as life's simple 7): smoking, dietary intake, physical activity, body mass index, blood pressure, glucose, and total cholesterol. We sought to expand the evidence for its utility to under-studied populations in sub-Saharan Africa, by determining its association with common carotid intima-media thickness (CIMT).

METHODS

We conducted a cross-sectional study involving 9011 participants drawn from Burkina Faso, Ghana, Kenya, and South Africa. We assessed established classical cardiovascular risk factors and measured carotid intima-media thickness of the left and right common carotid arteries using B-mode ultrasonography. Adjusted multilevel mixed-effect linear regression was used to determine the association of CVHI with common CIMT. In the combined population, an individual participant data meta-analyses random-effects was used to conduct pooled comparative sub-group analyses for differences between countries, sex, and socio-economic status.

RESULTS

The mean age of the study population was 51 ± 7 years and 51% were women, with a mean common CIMT of 637 ± 117 μm and CVHI score of 10.3 ± 2.0. Inverse associations were found between CVHI and common CIMT (β-coefficients [95% confidence interval]: Burkina Faso, - 6.51 [- 9.83, - 3.20] μm; Ghana, - 5.42 [- 8.90, - 1.95]; Kenya, - 6.58 [- 9.05, - 4.10]; and South Africa, - 7.85 [- 9.65, - 6.05]). Inverse relations were observed for women (- 4.44 [- 6.23, - 2.65]) and men (- 6.27 [- 7.91, - 4.64]) in the pooled sample. Smoking (p < 0.001), physical activity (p < 0.001), and hyperglycemia (p < 0.001) were related to CIMT in women only, while blood pressure and obesity were related to CIMT in both women and men (p < 0.001).

CONCLUSION

This large pan-African population study demonstrates that CVHI is a strong marker of subclinical atherosclerosis, measured by common CIMT and importantly demonstrates that primary prevention of atherosclerotic cardiovascular disease in this understudied population should target physical activity, smoking, obesity, hypertension, and hyperglycemia.

Performance of diabetes screening tests: an evaluation study of Iranian diabetes screening program

BACKGROUND

Type 2 diabetes is a common non-communicable disease that is responsible for about 9% of all deaths and a 25% reduction in life expectancy. However, nearly half of the diabetic patients are not aware of their disease. In this regard, to identify un-known diabetic patients, diabetes screening is of great importance. This study was conducted to evaluate the performance of two commonly used diabetes screening tests that are currently recommended by the Iranian diabetes screening program for (DSP).

METHODS

The validity of the two diabetes screening tests were measured among 1057 participants who were older than 30 years of age. The studied screening tests included capillary fasting blood glucose (CBG) and glycated hemoglobin (HbA1c). The golden standard for measuring the validity of the tests was venous fasting plasma glucose (VPG).

RESULTS

According to the results, the sensitivity of CBG and HbA1c tests was 69.01% and 84.5%, and the specificity of the tests were 95.7% and 79.3%, respectively. Positive and negative predictive values were 53.84% and 97.72% for CBG and 22.72% and 98.61% for HbA1c, respectively. The recommended cut points for CBG and HbA1c were 116.5 mg/dl and 7.15%, respectively. Using these values as the new cut points, sensitivity and specificity of CBG and HbA1c changed to 80.30% and 89.10%, and 77.50% and 94.20%, respectively.

CONCLUSIONS

Compared to several other countries, the performance of Iranian DSP is relatively better. The Receiver Operating Characteristic Curve suggested new cut points for significantly better performance of DSP.

Describing medicine therapy management of type 2 diabetes mellitus at primary health care facilities in Cape Town

Background

Rational medicine use aims to optimise chronic disease management and prevent episodes of hospitalisation that economically burden the health care system. Diabetes mellitus is one of the most prevalent chronic diseases globally, yet more than 60% of patients with diabetes are not optimally managed according to their therapeutic glycaemic targets.

Aim

To describe the use of glycated haemoglobin (HbA1c) and fasting plasma glucose results in guiding treatment changes in patients with type 2 diabetes mellitus.

Setting

Public sector primary health care facilities in the Cape Town Metropolitan Region in South Africa.

Method

Retrospective, descriptive study design was employed. Data for an 18-month period were collected during 2014 and 2015. Data were collected from patient medical records and included baseline demographics, laboratory monitoring tests and the patients' last three prescriptions.

Results

The study consisted of 575 participants (64% female) with an average age of 57 (± 11.38) years. The average baseline HbA1c for 493 participants with at least one result was 8.78% (± 1.63), and only 28% of these participants reached the glycaemic target at consequent consultations. HbA1c levels were available to guide 245 prescription changes, of which 181 of these results were outside of the target range. Of these, 15.5% had appropriate therapy adjustments, 78.4% had no change or a lateral change in their follow-up prescriptions, and 6.1% had therapy adjustments opposite to what guidelines suggest.

Conclusion

Glycaemic monitoring indicated consistent suboptimal glycaemic control in more than 60% of participants. Medicine prescribing patterns did not align with the prescribed local guidelines, Society for Metabolism, Endocrinology and Diabetes of South Africa (SEMDSA). The appropriate use and interpretation of HbA1c at a clinic level should be emphasised to promote rational use of medicines that minimise acute hospitalisation episodes and optimise patients' long-term health outcomes.

Glycated Hemoglobin in the Diagnosis of Diabetes Mellitus in a Semi-Urban Brazilian Population

The study evaluated glycated hemoglobin (HbA1c) as a diagnostic tool for diabetes and pre-diabetes in the Brazilian population. Further, the homeostasis model assessment of insulin resistance (HOMA-IR) was also examined against HbA1c values to identify the most suitable cut-off points for HOMA-IR to predict the risk of diabetes. A cross-sectional study was conducted among 714 randomly selected subjects. HbA1c, fasting, and 2 h plasma glucose values were measured. Insulin resistance estimates were calculated with HOMA-IR. The receiver operating characteristic curve assessed HbA1c performance. The adjusted prevalence rate of diabetes mellitus was 14.7%, and pre-diabetes 14.2%. The optimal HbA1c cut-off value was ≥6.8% for the diagnosis of diabetes, and ≥6.0% for pre-diabetes. The area under the curve using HbA1c was 0.85 (95% CI: 0.80–0.90) for detecting diabetes and 0.61 (95% CI: 0.55–0.67) for pre-diabetes. The optimal HOMA-IR cut-off value was 2.06 for HbA1c at 6.8%. The HbA1c cut-off value of ≥6.8% may be suitable for diagnosing diabetes in the Brazilian population. Our results do not support the use of HbA1c to diagnose pre-diabetes. A HOMA-IR cut-off point of 2.06 was a sensitive marker to assess the risk of diabetes.

Reference interval determination for glycated albumin in defined subgroups of a South African population

Background

Glycated proteins, such as glycated haemoglobin (HbA1c) and glycated albumin (GA%), are increasingly being used for glycaemic control assessment and the diagnosis of diabetes mellitus. GA% is an intermediate marker of glycaemic control that is not influenced by factors that affect HbA1c concentrations. The aim of this study was to determine reference intervals and assess confounding factors for glycated albumin in a well-characterized healthy population in South Africa.

Methods

We measured glycated albumin using an enzymatic method on stored serum samples of healthy individuals recruited in Cape Town, South Africa. Reference intervals (overall and specific for age, sex and ethnicity) were determined using non-parametric methods and confounding factors were assessed using multiple regression analysis.

Results

The reference interval (2.5th to 97.5th percentile) for glycated albumin of 663 healthy individuals (mean age, 34 years, 38.6% males) ranged from 10.7 to 15.2%. Sex, body mass index categories and ethnicity were significantly associated with the glycated albumin and were considered of practical importance because their standardized regression coefficients (Beta) were greater than a cut-off of 0.15, implying a stronger effect on glycated albumin ( P < 0.001). The glycated albumin reference intervals for subjects with body mass index <25 kg/m2 was 11.2–15.3%, for body mass index 25–30 kg/m2 it was 10.5–14.9% and 10.0–14.6% for body mass index >30 kg/m2 ( P = 0.0001).

Conclusions

The overall reference interval showed good correlation with reference intervals determined in other studies. However, sex, ethnicity and body mass index were statistically significant confounding factors that may influence the overall reference interval. Therefore, overall glycated albumin reference intervals should be used cautiously.

Glycated haemoglobin threshold for dysglycaemia screening, and application to metabolic syndrome diagnosis in HIV-infected Africans

BACKGROUND

Glycated haemoglobin (HbA1c) test has been increasingly promoted as an alternative to fasting plasma glucose (FPG) or oral glucose tolerance test (OGTT) to diagnose dysglycaemia but its performance in HIV-infected Africans has yet to be established. This study aimed to assess the diagnostic accuracy of HbA1c for dysglycaemia including FPG-defined and OGTT-defined dysglycaemia, and OGTT-defined diabetes in HIV-infected Africans, and the effect of HbA1c-predicted dysglycaemia on Joint Interim Statement (JIS)-based prevalent metabolic syndrome (MS).

METHODS

A cross-sectional study included HIV-positive patients recruited across public healthcare facilities in the Western Cape. The recommended HbA1c cut-points were tested alongside the optimal cut-points obtained from receiver operating characteristic curve analyses, while the agreement between the MS criteria were assessed using kappa statistic.

RESULTS

748 participants (157 men), median age 38 years, 93% on anti-retroviral drugs were included. The optimal HbA1c cut-points of 5.75% (39.3 mmol/mol) showed 54% sensitivity, 84% specificity for FPG-defined dysglycaemia, and 52% sensitivity, 85% specificity for OGTT-defined dysglycaemia. The HbA1c value of 5.85% (40.4 mmol/mol) (63% sensitivity, 99% specificity) was optimal for diabetes. The internationally advocated cut-point of 6.5% (48 mmol/mol) had 37% sensitivity and 99% specificity for diabetes, while HbA1c ≥5.7% (≥39 mmol/mol) yielded similar performance with the study-specific cut-point for any dysglycaemia. MS prevalence by the JIS criteria (28.2%) increased to 29.7% when using HbA1c ≥5.75% (≥39.3 mmol/mol) and to 32.9% with HbA1c ≥5.7% (≥39 mmol/mol); agreement between the original and modified criteria was generally good.

CONCLUSIONS

This study agrees with the internationally recommended HbA1c cut-point for detecting dysglycaemia, but not for diabetes in HIV-infected Africans. In line with previous studies in general African populations, our findings suggest that similar factors interfere with HbA1c values regardless of HIV infection status. Replacing FPG-based with HbA1c-predicted dysglycaemia in the JIS criteria to diagnose MS is feasible in HIV-infected Africans.

Changes in Obesity Phenotype Distribution in Mixed-ancestry South Africans in Cape Town Between 2008/09 and 2014/16

Background: The concept of obesity phenotypes encompasses a different approach to evaluating the relationship between obesity and cardiometabolic diseases. Considering the minimal research on obesity phenotypes in Africa, we investigated these changes from 2008/09 to 2014/16 in the mixed ancestry population in Cape Town, South Africa. Methods: In all, 928 (2008/09) and 1969 (2014/16) ≥20 year old participants were included in two community-based cross-sectional studies. For obesity phenotype classification, a combination of body mass index (BMI) categories and prevalent cardiometabolic disease risk factors were used, with the presence of ≥2 cardiometabolic abnormalities defining abnormal metabolic status. Interaction tests were used to investigate changes in their distribution across the years of study. Results: Distribution of BMI categories differed significantly between the 2 years; normal weight, overweight and obese: 27.4, 27.4, and 45.3% in 2008/09 vs. 34.2, 23.6, and 42.2% in 2014/16 (p = 0.001). There was no differential effect in the distribution of obesity phenotypes pattern across the two time-points (interaction p = 0.126). Across BMI categories, levels of cardiometabolic risk factors linearly deteriorated in both metabolically healthy and abnormal participants (all p ≤ 0.018 for linear trends). Findings were not sensitive to the number of metabolic abnormalities included in the definition of obesity phenotypes. Conclusions: Our study showed negligible differences in obesity phenotypes over time, but a high burden of metabolic abnormalities among normal weight participants, and a significant proportion of metabolically health obese individuals. Further investigation is needed to improve risk stratification and cost-effective identification of individuals at high risk for cardiometabolic diseases.

Evidence for the utility of antenatal HbA1c to predict early postpartum diabetes after gestational diabetes in South Africa

Aim To evaluate antenatal HbA1c at diagnosis and in the 4 weeks preceding delivery to predict early postpartum diabetes mellitus (DM) in women with Gestational Diabetes Mellitus (GDM). Methods Seventy-eight women with GDM were prospectively assessed. The ability of HbA1c at GDM diagnosis (t1) and in the 4 weeks preceding delivery (t2) to predict DM 6-12 weeks after delivery was investigated. Glucose assessment was performed between November 1, 2015, and November 1, 2016 at Tygerberg Hospital (TH), Cape Town, South Africa (SA). Individuals with known pre-existing diabetes were excluded. Results HbA1c of 6.2% (44 mmol/mol) and 6.5% (48 mmol/mol) at t1 predicted DM with sensitivities of 95% and 90% and specificities of 62% and 70% respectively. At t2 the best cut-off for HbA1c, in accordance with t1, was also 6.2% (44 mmol/mol; sensitivity 92%, specificity 56%). Nineteen of the 29 women with suspected pre-gestational DM had HbA1c levels ≥ 6.5% (48 mmol/mol) at t1. The increased risk for postpartum DM with HbA1c ≥ 6.2% (44 mmol/mol) was four-fold (OR 3.97 CI 2.08-7.59p < 0.001) at t1 and five-fold (OR 5.08 CI 1.60-16.25 p = 0.006) at t2. Conclusion HbA1c lower than 6.5% (48 mmol/mol) predicts postpartum DM in women with GDM. HbA1c can serve as instrument to improve postpartum follow-up.

Analysis of protein glycation in human fingernail clippings with near-infrared (NIR) spectroscopy as an alternative technique for the diagnosis of diabetes mellitus

Background:

Glycated keratin allows the monitoring of average tissue glucose exposure over previous weeks. In the present study, we wanted to explore if near-infrared (NIR) spectroscopy could be used as a non-invasive diagnostic tool for assessing glycation in diabetes mellitus.

Methods:

A total of 52 patients with diabetes mellitus and 107 healthy subjects were enrolled in this study. A limited number (n=21) of nails of healthy subjects were glycated in vitro with 0.278 mol/L, 0.556 mol/L and 0.833 mol/L glucose solution to study the effect of glucose on the nail spectrum. Consequently, the nail clippings of the patients were analyzed using a Thermo Fisher Antaris II Near-IR Analyzer Spectrometer and near infrared (NIR) chemical imaging. Spectral classification (patients with diabetes mellitus vs. healthy subjects) was performed using partial least square discriminant analysis (PLS-DA).

Results:

In vitro glycation resulted in peak sharpening between 4300 and 4400 cm−1 and spectral variations at 5270 cm−1 and between 6600 and 7500 cm−1. Similar regions encountered spectral deviations during analysis of the patients’ nails. Optimization of the spectral collection parameters was necessary in order to distinguish a large dataset. Spectra had to be collected at 16 cm−1, 128 scans, region 4000–7500 cm−1. Using standard normal variate, Savitsky-Golay smoothing (7 points) and first derivative preprocessing allowed for the prediction of the test set with 100% correct assignments utilizing a PLS-DA model.

Conclusions:

Analysis of protein glycation in human fingernail clippings with NIR spectroscopy could be an alternative affordable technique for the diagnosis of diabetes mellitus.

Derivation & validation of glycosylated haemoglobin (HbA 1c ) cut-off value as a diagnostic test for type 2 diabetes in south Indian population

Background & Objectives:

Glycosylated haemoglobin (HbA_1c) has been in use for more than a decade, as a diagnostic test for type 2 diabetes. Validity of HbA_1c needs to be established in the ethnic population in which it is intended to be used. The objective of this study was to derive and validate a HbA_1c cut-off value for the diagnosis of type 2 diabetes in the ethnic population of Rayalaseema area of south India.

Methods:

In this cross-sectional study, consecutive patients suspected to have type 2 diabetes underwent fasting plasma glucose (FPG) and 2 h post-load plasma glucose (2 h-PG) measurements after a 75 g glucose load and HbA_1c estimation. They were classified as having diabetes as per the American Diabetes Association criteria [(FPG ≥7 mmol/l (≥126 mg/dl) and/or 2 h-PG ≥11.1 mmol/l (≥200 mg/dl)]. In the training data set (n = 342), optimum cut-off value of HbA_1c for defining type 2 diabetes was derived by receiver-operator characteristic (ROC) curve method using oral glucose tolerance test results as gold standard. This cut-off was validated in a validation data set (n = 341).

Results:

On applying HbA_1c cut-off value of >6.3 per cent (45 mmol/mol) to the training data set, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for diagnosing type 2 diabetes were calculated to be 90.6, 85.2, 80.8 and 93.0 per cent, respectively. When the same cut-off value was applied to the validation data set, sensitivity, specificity, PPV and NPV were 88.8, 81.9, 74.0 and 92.7 per cent, respectively, although the latter were consistently smaller than the proportions for the training data set, the differences being not significant.

Interpretation & conclusions:

HbA_1c >6.3 per cent (45 mmol/mol) appears to be the optimal cut-off value for the diagnosis of type 2 diabetes applicable to the ethnic population of Rayalaseema area of Andhra Pradesh state in south India.

High Molecular Weight Adiponectin Levels are Neither Influenced by Adiponectin Polymorphisms Nor Associated with Insulin Resistance in Mixed-ancestry Hyperglycemic Subjects from South Africa

Background

High molecular weight (HMW) adiponectin has antiatherogenic, antiinflammatory and antidiabetic properties and these effects have been linked to its effect on high density lipoprotein cholesterol (HDL-c). Single nucleotide polymorphisms (SNPs) in the adiponectin gene influence adiponectin levels. We examined the relationship between HMW-adiponectin levels and cardiometabolic traits in normo- and hyperglycemic mixed ancestry South Africans and correlated these levels to two common polymorphisms.

Methods

HMW-adiponectin was determined in 101 subjects from the Cape Town Bellville South community-based study on a mixed ancestry population. Comparisons were made between individuals with normo- and hyperglycemia. Two common SNPs, ADIPOQ SNPs rs17300539 and rs266729, known to affect adiponectin levels were also tested for. Levels of HMW-adiponectin were then correlated with cardiometabolic traits in all groups.

Results

Levels of HMW-adiponectin were not significantly different in the normo- and hyperglycemic groups (median 11.6 vs. 10.5 μg/mL, p=0.3060) and in men and women (8.44 vs. 11.34 μg/mL, p=0.67). ADIPOQ SNPs rs17300539 and rs266729 did not influence levels of HMW-adiponectin. Robust correlation analyses revealed a significant positive correlation between HMW-adiponectin and HDL-c (r=0.45; 95%CI: 0.27–0.59), similarly in normo- and hyperglycemic participants (p > 0.99). This association was substantially attenuated in robust linear regressions adjusted for age, gender and adiposity.

Conclusions

Adiponectin levels in this population were not determined by the commonest SNPs of the adiponectin gene, were unaffected by glycemic status; but were significantly correlated with HDL-c levels. Previous studies have attributed some of the beneficial effects of adiponectin to its effect on HDL-c.

Correlation of E-selectin concentrations with carotid intima-media thickness and cardio-metabolic profile of mixed ancestry South Africans: a cross-sectional study

Background E-selectin, an adhesion molecule, is a specific marker of endothelial dysfunction. High concentrations have been reported in type 2 diabetes and disorders with high risk of cardiovascular disease (CVD). Measurement of carotid intima-media thickness (CIMT) is a surrogate marker of early atherosclerosis. We examined the relationship between E-selectin concentrations, CIMT and cardio-metabolic traits in normo- and hyperglycaemic mixed ancestry South Africans. Methods E-selectin concentrations were determined in 308 subjects from the Cape Town Bellville South Community-based study on a mixed ancestry population. Their correlation with CIMT and cardio-metabolic profile used robust correlations and linear regression models. Results E-selectin concentrations were significantly higher in the hyperglycaemic (median 139.8 µg/L) compared to the normoglycaemic group (median 118.8 µg/L), ( p = 0.0007). Significant differences between the two groups were found for markers of glycaemia and adiposity, but not for CIMT. Significant correlations were found between E-selectin and age, markers of glycaemia and inflammation, central obesity and lipid variables. Associations remained significant only with age, hyperglycaemia and C-reactive protein in robust linear regression models. In similar regressions models, age and gender were the main predictors of CIMT, which was not associated with E-selectin. Conclusions E-selectin concentrations in this study were associated with hyperglycaemia, possibly reflecting early endothelial damage. However, E-selectin was not useful to assess CIMT, a marker of subclinical atherosclerosis, which appeared to be determined by ageing and male gender.

Glucose Tolerance, MTHFR C677T and NOS3 G894T Polymorphisms, and Global DNA Methylation in Mixed Ancestry African Individuals

The aim of this study is to quantify global DNA methylation and investigate the relationship with diabetes status and polymorphisms in MTHFR C677T and NOS3 G894T genes in mixed ancestry subjects from South Africa. Global DNA methylation was measured, and MTHFR rs1801133 and NOS3 rs1799983 polymorphisms were genotyped using high throughput real-time polymerase chain reaction and direct DNA sequencing. Of the 564 participants, 158 (28%) individuals had T2DM of which 97 (17.2%) were screen-detected cases. Another 119 (21.1%) had prediabetes, that is, impaired fasting glucose, impaired glucose tolerance, or the combination of both, and the remainder 287 (50.9%) had normal glucose tolerance. Global DNA methylation was significantly higher in prediabetes and screen-detected diabetes than in normal glucose tolerance (both p ≤ 0.033) and in screen-detected diabetes compared to known diabetes on treatment (p = 0.019). There was no difference in global DNA methylation between known diabetes on treatment and normal glucose tolerance (p > 0.999). In multivariable linear regression analysis, only NOS3 was associated with increasing global DNA methylation (β = 0.943; 95% CI: 0.286 to 1.560). The association of global DNA methylation with screen-detected diabetes but not treated diabetes suggests that glucose control agents to some extent may be reversing DNA methylation. The association between NOS3 rs1799983 polymorphisms and DNA methylation suggests gene-epigenetic mechanisms through which vascular diabetes complications develop despite adequate metabolic control.

Contribution of ENPP1, TCF7L2, and FTO polymorphisms to type 2 diabetes in mixed ancestry ethnic population of South Africa

BACKGROUND

Transcription factor 7-like 2 gene (TCF7L2), fat mass and obesity-associated gene (FTO), and ectonucleotide pyrophosphatase/phosphodiesterase gene (ENPP1) are known risk loci for type 2 diabetes (T2DM) mostly in European populations.

OBJECTIVES

To assess the association of these genes with T2DM risk in a South African mixed-ancestry population.

METHODS

Five hundred and sixty six participants were genotyped for ENPP1-rs997509 and -rs1044498, FTO-9941349 and -rs3751812, TCF7L2-rs12255372 and -rs7903146 polymorphisms using Taqman genotyping assays and validated by automated sequencing to assess the association of the polymorphisms with cardiometabolic traits.

RESULTS

In logistic regression models adjusted for age, sex, body mass index (BMI) and insulin resistance, minor allele of rs997509 was associated with a higher risk of prevalent T2DM under a recessive model [odd ratio 4.60 (95% confidence interval: 1.07 to 19.86); p = 0.040].Under additive model, the rs7903146 [1.43 (1.00 to 2.04); p= 0.053] and rs9941349 [1.43 (1.00 to 2.04); p = 0.052] minor alleles showed marginally significant associations with a high risk of T2DM. However, only the rs7903146 alleles (p=0.011) and genotypes (p=0.025) distributions were statistically significantly different between diabetic and non-diabetic individuals.

CONCLUSION

Our findings demonstrate that ENPP1, TCF7L2, and FTO may predispose to T2DM in the mixed-ancestry population.

Prevalence of undiagnosed diabetes and pre-diabetes among hypertensive patients attending Kiambu district Hospital, Kenya: a cross-sectional study

INTRODUCTION

Hypertension (HTN) and diabetes mellitus (DM) are two common non-communicable diseases (NCDs) that are closely linked: one cannot be properly managed without attention to the other. The aim of this study was to determine the prevalence of undiagnosed diabetic and pre-diabetic states that is abnormal glucose regulation (AGR) and factors associated with it among hypertensive patients in Kiambu Hospital, Kenya.

METHODS

We conducted a cross-sectional study from February 2014 to April 2014. Hypertensive patients aged ≥ 18 attending the out-patient medical clinic were included in the study. Pregnant and known diabetic patients were excluded. Data was collected on socio-demographics, behavior, and anthropometrics. Diabetes status was based on a Glycated Haemoglobin (HbA1C) classification of ≥ 6.5% for diabetes, 6.0-6.4% for pre-diabetes and ≤ 6.0% for normal. AGR was the dependable variable and included two diabetic categories; diabetes and pre-diabetes.

RESULTS

We enrolled 334 patients into the study: the mean age was 59 years (Standard deviation = 14.3). Of these patients 254 (76%) were women. Thirty two percent (107/334; 32%) were found to have AGR, with 14% (46) having un-diagnosed DM and 18%(61) with pre-diabetes. Factors associated with AGR were age ≥ 45 (OR = 3.23; 95% CI 1.37 ≥ 7.62), basal metabolic index (BMI) ≥ 25 Kg/m(2) (OR = 3.13; 95% CI 1.53 - 6.41), low formal education (primary/none)(OR= 2; 95%CI 1.08 - 3.56) and family history of DM (OR = 2.19; 95%CI 1.16 - 4.15).

CONCLUSION

There was a high prevalence of undiagnosed AGR among hypertensive patients. This highlights the need to regularly screen for AGR among hypertensive patients as recommended by WHO.

APOL1 genetic variants, chronic kidney diseases and hypertension in mixed ancestry South Africans

Background

The frequencies of apolipoprotein L1 (APOL1) variants and their associations with chronic kidney disease (CKD) vary substantially in populations from Africa. Moreover, available studies have used very small sample sizes to provide reliable estimates of the frequencies of these variants in the general population. We determined the frequency of the two APOL1 risk alleles (G1 and G2) and investigated their association with renal traits in a relatively large sample of mixed-ancestry South Africans. APOL1 risk variants (G1: rs60910145 and rs73885319; G2: rs71785313) were genotyped in 859 African mixed ancestry individuals using allele-specific TaqMan technology. Glomerular filtration rate (eGFR) was estimated using the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations.

Results

The frequencies of rs73885319, rs60910145 and rs71785313 risk alleles were respectively, 3.6 %, 3.4 %, and 5.8 %, resulting in a 1.01 % frequency of the APOL1 two-risk allele (G1:G1 or G1:G2 or G2:G2). The presence of the two-risk allele increased serum creatinine with a corresponding reduction in eGFR (either MDRD or CKD-EPI based). In dominant and log-additive genetic models, significant associations were found between rs71785313 and systolic blood pressure (both p ≤ 0.025), with a significant statistical interaction by diabetes status, p = 0.022, reflecting a negative non-significant effect in nondiabetics and a positive effect in diabetics.

Conclusions

Although the APOL1 variants are not common in the mixed ancestry population of South Africa, the study does provide an indication that APOL1 variants may play a role in conferring an increased risk for renal and cardiovascular risk in this population.

Level of sustained glycemic control and associated factors among patients with diabetes mellitus in Ethiopia: a hospital-based cross-sectional study

BACKGROUND

The level of sustained glycemic control in patients with diabetes mellitus (DM) is a major determinant of the occurrence of both acute and chronic complications. However, information about the level of glycemic control among patients in the follow-up care at the University of Gondar Referral Hospital is scanty. The study assessed the degree of glycemic control and associated factors among diabetic patients in the study area.

METHOD

A hospital-based cross-sectional study was conducted at the University of Gondar Referral Hospital. All diabetic patients aged ≥18 years who visited the Diabetes Clinic in January and February 2013 for follow-up medical evaluation and medication participated in the study. Patients with glycosylated hemoglobin test (HbA1c) of ≥7% were classified as having a poor level of glycemic control. Propensity score was used to estimate the treatment effect. Multivariable logistic regression analysis was applied to determine the associated factors.

RESULT

Two hundred and fifty three (64.7%) of the 391 diabetic patients included in the study had a poor level of glycemic control, as evidenced by HbA1c ≥7%. Poor glycemic control was much higher among Type 1 patients (82.9%) compared with Type 2 patients (57.5%). Being on insulin treatment (AOR =2.51; 95% CI =1.25, 5.04) and reporting poor medication adherence (AOR =3.19; 95% CI =1.76, 5.80) were found to be associated with poor glycemic control among Type 2 DM patients. High waist circumference was inversely associated with a poor level of glycemic control in Type 1 DM patients (AOR =0.05; 95% CI =0.01, 0.85).

CONCLUSION

The proportion of diabetic patients with a poor level of glycemic control is high. We recommend a comprehensive intervention to improve the overall treatment adherence with special attention to DM patients receiving insulin.

Glycated hemoglobin for the diagnosis of diabetes and prediabetes: Diagnostic impact on obese and lean subjects, and phenotypic characterization

Aims/Introduction

Measurement of glycated hemoglobin (HbA1c) has been recommended for the diagnosis of diabetes and prediabetes. However, epidemiological studies have shown significant discordance between HbA1c and glucose-based tests. Of the factors that could influence agreement between HbA1c and the oral glucose tolerance test (OGTT), bodyweight has not been fully evaluated. The aims of the present study were to evaluate the impact of HbA1c criteria to diagnose diabetes and prediabetes compared with OGTT, and to examine HbA1c in relation to body mass index.

Materials and Methods

Two cohorts were studied, one from an obesity clinic (n = 592) and one from subjects undergoing screening for diabetes (n = 462). All underwent OGTT and HbA1c measurement.

Results

In the obese cohort, HbA1c ≥6.5% (≥48 mmol/mol) showed a sensitivity of 69.3% for diabetes, whereas HbA1c 5.7–6.4% (39–46 mmol/mol) did not identify prediabetes well (sensitivity 39.1%). In the diabetes screening cohort, HbA1c had low sensitivities for both diabetes (39.2%) and prediabetes (53.3%). When participants were stratified according to body mass index class I–III, HbA1c agreement with the OGTT for diabetes was much higher (80%, P < 0.005) in class I obesity compared with class II–III obesity; whereas for prediabetes, HbA1c had a low sensitivity in all obesity classes.

Conclusions

The agreement between HbA1c, fasting plasma glucose and 2-h glucose post-OGTT for the diagnosis of prediabetes was poor in our Italian population; whereas HbA1c ≥6.5% showed a relatively good agreement with OGTT for the diagnosis of diabetes. For the first time, we have shown that obesity class influences the diagnostic performance of HbA1c.

Rare mutations of peroxisome proliferator-activated receptor gamma: frequencies and relationship with insulin resistance and diabetes risk in the mixed ancestry population from South Africa

Background. Genetic variants in the nuclear transcription receptor, PPARG, are associated with cardiometabolic traits, but reports remain conflicting. We determined the frequency and the clinical relevance of PPARG SNPs in an African mixed ancestry population. Methods. In a cross-sectional study, 820 participants were genotyped for rs1800571, rs72551362, rs72551363, rs72551364, and rs3856806, using allele-specific TaqMan technology. The homeostatic model assessment of insulin (HOMA-IR), β-cells function (HOMA-B%), fasting insulin resistance index (FIRI), and the quantitative insulin-sensitivity check index (QUICKI) were calculated. Results. No sequence variants were found except for the rs3856806. The frequency of the PPARG-His447His variant was 23.8% in the overall population group, with no difference by diabetes status (P = 0.215). The His447His allele T was associated with none of the markers of insulin resistance overall and by diabetes status. In models adjusted for 2-hour insulin, the T allele was associated with lower prevalent diabetes risk (odds ratio 0.56 (95% CI 0.31-0.95)). Conclusion. Our study confirms the almost zero occurrences of known rare PPARG SNPs and has shown for the first time in an African population that one of the common SNPs, His447His, may be protective against type 2 diabetes.

Prevalence of diabetes in Malaysia and usefulness of HbA1c as a diagnostic criterion

AIM

The prevalence of diabetes mellitus among Malaysians aged ≥ 30 years of age has increased by more than twofold over a 20-year period. This study aimed to determine the current status and to evaluate the diagnostic usefulness of the HbA(1c) cut-off point of 48 mmol/mol (6.5%).

METHODS

Using a two-stage stratified sampling design, participants aged ≥ 18 years were recruited from five zones selected to represent Malaysia. An oral glucose tolerance test was performed on all those not known to have diabetes.

RESULTS

A total of 4341 subjects were recruited. By World Health Organization criteria, the prevalence of diabetes mellitus was 22.9%; of that percentage, 10.8% was known diabetes and 12.1% was newly diagnosed diabetes. Diabetes was most prevalent amongst Indians (37.9%) and Malays (23.8%). Prevalence of new diabetes mellitus was only 5.5% (95% CI 4.9-6.3) when based on the HbA(1c) diagnostic criteria of 48 mmol/mol (6.5%) and, although the cut-off point was highly specific (98.1%), it was less sensitive (36.7%) compared with 45 mmol/mol (6.3%), which showed the optimal sum of sensitivity (42.5%) and specificity (97.4%) in identifying new diabetes mellitus.

CONCLUSION

This study recorded an overall diabetes prevalence of 22.6%, almost a twofold increase from 11.6% reported in 2006. This was likely attributable to the higher prevalence of new diabetes (12.1%) diagnosed following an oral glucose tolerance test. An HbA(1c) of 45 mmol/mol (6.3%) was found to be a better predictive cut-off point for detecting new diabetes in our multi-ethnic population.

Diagnostic accuracy of HbA1c in diabetes between Eastern and Western

BACKGROUND

In 2010, the American Diabetes Association recommended the use of HbA1c as a diagnostic criterion for diabetes. However, HbA1c is not an accepted diagnostic tool for diabetes in Eastern Asia, because genetic differences compromise the standardization of the diagnostic cut-off point.

OBJECTIVES

This study evaluated differences in the use of HbA1c for diagnosing diabetes in Eastern and Western populations and investigated whether HbA1c cut-off point of ≥ 6.5% is diagnostic of diabetes in patients from Eastern Asia.

METHODS

Literature was obtained from MEDLINE, EMBASE and Cochrane databases. The pooled sensitivity and specificity of each HbA1c cut-off point were extracted and compared between Western and Eastern populations. Differences in the cut-off point for diagnosing diabetes in each region were compared by examining differences in the area under summary receiver operating characteristic (SROC) curves.

RESULTS

Twelve publications from Eastern countries (n = 59,735) and 13 from Western countries (n = 22,954) were included in the analysis. Areas under SROC curves in the Eastern and Western groups were 0.9331 and 0.9120, respectively (P = 0.98). The cut-off point of the highest Youden index was 6.0%. At the HbA1c cut-off point of 6.5%, the pooled sensitivity and specificity were 58.7% and 98.4% for Eastern countries and 65.5% and 98.1% for Western countries, respectively.

CONCLUSIONS

HbA1c exhibits the same diagnostic value for diabetes in Eastern and Western populations. In both populations, HbA1c levels > 6.0% identify the population at high risk of diabetes, and HbA1c > 6.5% is diagnostic of clinically established diabetes.

Chronic kidney diseases in mixed ancestry south African populations: prevalence, determinants and concordance between kidney function estimators

BACKGROUND

Population-based data on the burden of chronic kidney disease (CKD) in sub-Saharan Africa is still very limited. We assessed the prevalence and determinants of CKD, and evaluated the concordance of commonly advocated estimators of glomerular filtration rate (eGFR) in a mixed ancestry population from South Africa.

METHODS

Participants were a population-based sample of adults selected from the Bellville-South community in the metropolitan city of Cape Town. eGFR was based on the Cockroft-Gault (CG), Modification of Diet in Kidney Disease (MDRD) and CKD Epidemiology Collaboration (CKD-EPI) equations (with and without adjustment for ethnicity). Kidney function staging used the Kidney Disease Outcome Quality Initiative (KDOQI) classification. Logistic regressions and kappa statistic were used to investigate determinants of CKD and assess the agreement between different estimators.

RESULTS

The crude prevalence of CKD stage 3-5 was 14.8% for Cockcroft-Gault, 7.6% and 23.9% respectively for the MDRD with and without ethnicity correction, and 7.4% and 17.3% for the CKD-EPI equations with and without ethnicity correction. The highest agreement between GFR estimators was between MDRD and CKD-EPI equations, both with ethnicity correction, Kappa 0.91 (95% CI: 0.86-0.95), correlation coefficient 0.95 (95% CI: 0.94-0.96). In multivariable logistic regression models, sex, age and known hypertension were consistently associated with CKD stage 3-5 across the 5 estimators.

CONCLUSIONS

The prevalence of CKD stages greater than 3 is the highest reported in Africa. This study provides evidence for support of the CKD-EPI equation for eGFR reporting and CKD classification.

Three-year's changes in glucose tolerance status in the Bellville South cohort: rates and phenotypes associated with progression

AIMS

To determine the phenotypes associated with progression to type 2 diabetes or worsening in glucose tolerance during a 3-year follow-up of a community-based cohort in Cape Town, South Africa.

METHODS

A total of 198 eligible subjects (72.3% women) aged 55.2 years, from the Bellville-South community were followed-up between 2008 and 2011. Baseline and follow-up data collections included glucose tolerance status, anthropometric, blood pressure, lipids, insulin, γ-glutamyltransferase, cotinine, creatinine and HbA1c. Progression in glucose tolerance status at 3-year was the composite of new-onset diabetes and any worsening in glucose tolerance status.

RESULTS

The cumulative incidence of progression in glucose tolerance status was: 16.2% (32 participants including 11 with new-onset diabetes), and increased in a stepwise fashion with the number of components of metabolic syndrome (MetS). In age and sex-adjusted logistic regression analyses, MetS [odd ratio: 3.08 (95% CI: 1.34-7.10)], HbA1c [5.26 (1.94-14.24)], HDL-cholesterol [0.05 (0.01-0.33)], γ-glutamyltransferase [1.99 (1.07-3.67)], triglycerides [1.71 (1.13-2.58)] and total/HDL-cholesterol [1.45 (1.08-1.93)] were significant predictors of progression, while borderline effects were observed for baseline glucose and diastolic blood pressure. Markers of adiposity were mostly stable or improved among non-progressors during follow-up, but deteriorated significantly among progressors, resulting in significant statistical interactions.

CONCLUSIONS

High rates of deterioration of glucose status over time were found in our population, with nearly one-fifth of them acquiring a glucose tolerance worse status within a very short follow-up. Our study extends to this setting the well-known utility of phenotypes of MetS single or in combination, in predicting worsening in glucose tolerance status.

Polymorphisms in the non-muscle myosin heavy chain gene (MYH9) are associated with lower glomerular filtration rate in mixed ancestry diabetic subjects from South Africa

Objective

Though single nucleotide polymorphisms (SNPs) in the non-muscle myosin gene (MYH9) have been reported to explain most of the excess risk of nondiabetic chronic kidney disease (CKD), in African-Americans, some studies have also shown associations with diabetic end-stage renal disease. We investigated the association of MYH9 SNPs with renal traits in a mixed-ancestry South African population prone to diabetes.

Research Design and Methods

Three SNPs known to be associated with CKD (rs4821480, rs5756152 and rs12107) were genotyped using Taqman assay in 716 adults (198 with diabetes) from the Bellville-South community, Cape Town. Glomerular filtration rate was estimated (eGFR) and urinary albumin/creatinine ratio (ACR) assessed. Multivariable regressions were used to relate the SNPs with renal traits.

Results

Mean age was 53.6 years, with the expected differences observed in characteristics by diabetic status. Significant associations were found between rs575152 and serum creatinine, and eGFR in the total population, and in diabetic participants (all p≤0.003), but not in non-diabetics (all p≥0.16), with significant interactions by diabetes status (interaction-p≤0.009). The association with ACR was borderline in diabetic participants (p = 0.05) and non-significant in non-diabetics (p = 0.85), with significant interaction (interaction p = 0.02). rs12107 was associated with fasting-, 2-hour glucose and HbA1c in diabetic participants only (interaction-p≤0.003), but not with renal traits.

Conclusion

MYH9 SNPs were associated with renal traits only in diabetic participants in this population. Our findings and other studies suggest that MYH9 may have a broader genetic risk effect on kidney diseases.

Exploring leukocyte O-GlcNAcylation as a novel diagnostic tool for the earlier detection of type 2 diabetes mellitus

CONTEXT

Because current tests available for the diagnosis of diabetes have shortcomings, a novel screening method for the earlier and more efficient detection of type 2 diabetes would be a significant clinical advance.

OBJECTIVE

The hexosamine biosynthetic pathway usually acts as a fuel sensor, and its activation leads to O-linked β-N-acetylglucosamine (O-GlcNAc) modification of target proteins (O-GlcNAcylation) in a glucose-responsive manner. O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) are responsible for O-GlcNAc addition and removal, respectively. Because higher hexosamine biosynthetic pathway flux is linked to insulin resistance/type 2 diabetes, we hypothesized that increased O-GlcNAcylation of leukocyte proteins can detect the onset of pre- and overt diabetes.

DESIGN, SETTING AND PATIENTS

Seventy-four participants from Bellville and Stellenbosch (Western Cape, South Africa) were recruited and classified as normal, prediabetic, and diabetic individuals (American Diabetes Association criteria).

MAIN OUTCOME MEASURES

Leukocytes isolated from study subjects were evaluated for O-GlcNAc, OGA, and O-GlcNAc transferase expression by flow cytometry and immunofluorescence microscopy.

RESULTS

Flow cytometric analysis of leukocyte subtypes revealed increased O-GlcNAcylation in granulocytes vs. lymphocytes (P < 0.001). Diabetic individuals displayed higher leukocyte O-GlcNAcylation (P < 0.01), whereas granulocyte analysis showed an increase for prediabetic subjects (P < 0.01). However, OGA expression increased in leukocytes of diabetic subjects and is likely an adaptation to attenuate higher O-GlcNAcylation observed (P < 0.001).

CONCLUSIONS

Together our data demonstrate that leukocyte (particularly granulocyte) O-GlcNAcylation could help detect pre- and overt diabetes and offer clinical value as unique markers for the earlier and more efficient detection of type 2 diabetes.

The current waist circumference cut point used for the diagnosis of metabolic syndrome in sub-Saharan African women is not appropriate

The waist circumference cut point for diagnosing the metabolic syndrome in sub-Saharan African subjects is based on that obtained from studies in European populations. The aim of this study was to measure the prevalence of obesity and related metabolic disorders in an urban population of African females, a group at high risk for such diseases, and to determine the appropriate waist cut point for diagnosing the metabolic syndrome. Anthropometry and fasting lipid, glucose and insulin levels were measured in a cohort of 1251 African females participating in the Birth to Twenty cohort study in Soweto, Johannesburg. The waist circumference cut points for diagnosing metabolic syndrome (as defined using the new harmonised guidelines), insulin resistance, dysglycaemia, hypertension and dyslipidaemia were obtained using receiver operator characteristic curve analysis. The prevalence of obesity, type 2 diabetes and metabolic syndrome were 50.1%, 14.3% and 42.1%, respectively. The appropriate waist cut point for diagnosing metabolic syndrome was found to be 91.5 cm and was similar to the cuts points obtained for detecting increased risk of insulin resistance (89.0 cm), dysglycaemia (88.4 cm), hypertension (90.1 cm), hypo-high density lipoproteinaemia (87.6 cm) and hyper-low density lipoproteinaemia (90.5 cm). The present data demonstrates that urban, African females have a high prevalence of obesity and related disorders and the waist cut point currently recommended for the diagnosis of the metabolic syndrome (80.0 cm) in this population should be increased to 91.5 cm. This latter finding demonstrates a clear ethnic difference in the relationship between abdominal adiposity and metabolic disease risk. The similar waist cut points identified for the detection of the individual components of the metabolic syndrome and related cardiovascular risk factors demonstrates that the risk for different metabolic diseases increases at the same level of abdominal adiposity suggesting a common aetiological pathway.