Should haemoglobin A1C be used for diagnosis of diabetes mellitus in Malawi?

Waist circumference and glycaemia are strong predictors of progression to diabetes in individuals with prediabetes in sub-Saharan Africa: 4-year prospective cohort study in Malawi

Sub-Saharan Africa is projected to have the highest increase in the number of people with diabetes worldwide. However, the drivers of diabetes in this region have not been clearly elucidated. The aim of this study was to evaluate the incidence of diabetes and the predictors of progression in a population-based cohort with impaired fasting glucose (IFG) in Malawi. We used data from an extensive rural and urban non-communicable disease survey. One hundred seventy-five, of 389 individuals with impaired fasting glucose (IFG) at baseline, age 48 ±15 years and body mass index 27.5 ±5.9 kg/m2 were followed up for a median of 4.2 years (714 person-years). Incidence rates were calculated, and predictors of progression to diabetes were analysed using multivariable logistic regression models, with overall performance determined using receiver operator characteristics (ROC) curves. The median follow-up was 4.2 (IQR 3.4-4.7) years. Forty-five out of 175 (26%) progressed to diabetes. Incidence rates of diabetes were 62.9 per 1000 person-years 95% CI, 47.0-84.3. The predictors of progression were higher; age (odds ratio [OR] 1.48, P = 0.046), BMI (OR 1.98, P = 0.001), waist circumference (OR 2.50,P<0.001), waist-hip ratio (OR 1.40, P = 0.03), systolic blood pressure (OR 1.56, P = 0.01), fasting plasma glucose (OR 1.53, P = 0.01), cholesterol (OR 1.44, P = 0.05) and low-density lipoprotein cholesterol (OR 1.80, P = 0.002). A simple model combining fasting plasma glucose and waist circumference was predictive of progression to diabetes (ROC area under the curve = 0.79). The incidence of diabetes in people with IFG is high in Malawi and predictors of progression are like those seen in other populations. Our data also suggests that a simple chart with probabilities of progression to diabetes based on waist circumference and fasting plasma glucose could be used to identify those at risk of progression in clinical settings in sub-Saharan Africa.

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.

High prevalence and heterogeneity of Dysglycemia in patients with tuberculosis from Peru: a prospective cohort study

BACKGROUND

The accuracy of different laboratory tests for diagnosis of diabetes mellitus (DM) and prediabetes (preDM) in populations exposed to tuberculosis (TB) remains poorly understood. Here, we examined the prevalence of DM and preDM in TB affected people in Lima, Peru.

METHODS

A prospective cohort study of patients affected TB and their household contacts (HHC), was conducted between February and November 2017 in Lima, Peru. Fasting plasma glucose (FPG), HbA1c and oral glucose tolerance test (OGTT) were used to detect DM and preDM in a prospective cohort of TB patients (n = 136) and household contacts (n = 138). Diagnostic performance of the laboratory tests was analyzed. Potential effects of sociodemographic and clinical factors on detection of dysglycemia were analyzed.

RESULTS

In TB patients, prevalence of DM and preDM was 13.97 and 30.88% respectively. Lower prevalence of both DM (6.52%) and preDM (28.99%) were observed in contacts. FPG, HbA1c and OGTT had poor agreement in detection of preDM in either TB cases or contacts. TB-DM patients had substantially lower hemoglobin levels, which resulted in low accuracy of HbA1c-based diagnosis. Classic sociodemographic and clinical characteristics were not different between TB patients with or without dysglycemia.

CONCLUSION

High prevalence of DM and preDM was found in both TB patients and contacts in Lima. Anemia was strongly associated with TB-DM, which directly affected the diagnostic performance of HbA1c in such population.

Diabetes mellitus and laboratory medicine in sub-Saharan Africa: challenges and perspectives

Diabetes mellitus is an increasing public health problem in sub-Saharan Africa with a substantial socioeconomic burden. Although laboratory medicine has been recognized as one of the six key public health functions, there are still gaps in strengthening of laboratory services in developing countries. In the last decades, a lot of progress has been made in the diagnostic field of infectious diseases, whereas the diagnosis of noncommunicable diseases is still insufficient and uneven. This article analyses the challenges encountered in diagnosing and monitoring of diabetes mellitus in sub-Saharan Africa and explores new alternative diagnostic tools.

Glycated haemoglobin A1c (HbA1c) for detection of diabetes mellitus and impaired fasting glucose in Malawi: a diagnostic accuracy study

OBJECTIVES

To examine the accuracy of glycated haemoglobin A_1c (HbA_1c) in detecting type 2 diabetes and impaired fasting glucose among adults living in Malawi.

DESIGN

A diagnostic validation study of HbA_1c. Fasting plasma glucose (FPG) ≥7.0 mmol/L was the reference standard for type 2 diabetes, and FPG between 6.1 and 6.9 mmol/L as impaired fasting glucose.

PARTICIPANTS

3645 adults (of whom 63% were women) recruited from two demographic surveillance study sites in urban and rural Malawi. This analysis excluded those who had a previous diagnosis of diabetes or had history of taking diabetes medication.

RESULTS

HbA_1c demonstrated excellent validity to detect FPG-defined diabetes, with an area under the receiver operating characteristic (AUROC) curve of 0.92 (95% CI 0.90 to 0.94). At HbA_1c ≥6.5% (140 mg/dL), sensitivity was 78.7% and specificity was 94.0%. Subgroup AUROCs ranged from 0.86 for participants with anaemia to 0.94 for participants in urban Malawi. There were clinical and metabolic differences between participants with true diabetes versus false positives when HbA_1c was ≥6.5% (140 mg/dL).

CONCLUSIONS

The findings from this study provide justification to use HbA_1c to detect type 2 diabetes. As HbA_1c testing is substantially less burdensome to patients than either FPG testing or oral glucose tolerance testing, it represents a useful option for expanding access to diabetes care in sub-Saharan Africa.