Once thought to be rare in sub-Saharan Africa (SSA), an estimated 20 million adults are now living with diabetes, a burden that is predicted to more than double by 2035.(1) There is a critical need for a reliable, convenient, high performance, low cost biochemical test to improve detection of undiagnosed diabetes in this setting.
Diabetes is a chronic condition that occurs when a person has higher-than-healthy blood glucose levels due to abnormal insulin production or action. Early diagnosis and management of diabetes is essential to mitigate the development of severe complications.(2) However, nearly two-thirds of people with diabetes in SSA are undiagnosed, the highest proportion of any region in the world.(1)
The current WHO gold standard for diabetes diagnosis is the oral glucose tolerance test (OGTT), which measures plasma glucose levels in the blood. The OGTT is a cheap way to diagnose diabetes in resource poor settings; however it requires fasting overnight and immediate lab testing. In 2011, the WHO recommended glycated haemoglobin (HbA1c) for diagnosis alongside the OGTT. HbA1c is formed when haemoglobin in red blood cells joins with glucose in the blood. These cells survive for 8-12 weeks, therefore measuring HbA1c levels can be used to estimate the average blood glucose levels over this period, a useful indicator of prolonged high blood glucose.(3)
HbA1c may have several advantages for use in African populations over glucose-based measurements such as OGTT. HbA1c does not require fasting overnight, potentially a major barrier in rural areas where travelling long distances to health facilities is common. Additionally, it does not require immediate lab handling and can be easily stored and transported.(4) Monitoring blood glucose with HbA1c has been a cornerstone of diabetes management in many countries for decades and has been shown to lead to improved diabetic control in some SSA settings.(5) Therefore, any strengthening of access to HbA1c testing for diagnosis will also improve the on-going management of the condition.
However, use of HbA1c has several limitations within SSA populations. First, it is expensive in comparison to OGTT. Secondly, being a blood based marker, any condition that affects the blood or blood cell production could affect the HbA1c test, for example, sickle cell disease. Furthermore, chronic infections can affect the performance of HbA1c, a real issue given the prevalence of HIV, malaria and other infectious diseases in some SSA populations. HbA1c testing also requires standardised laboratories and equipment and, whilst this is becoming more common across the region, access is still limited.(6)
Caution is always necessary when considering implementation of a test to diagnose and manage individuals, especially in already over-burdened and under-resourced health systems. Prospective studies are needed to determine the performance of HbA1c for diagnosing diabetes and predicting future diabetes complications in African populations where the effects of chronic infections and blood disorders on its usefulness as a biochemical test are unknown. Ultimately, in order to avoid a huge health and economic burden from diabetes in the next few decades, it is essential that experimentation and evaluation of developments in the diagnosis and management of diabetes is pursued in this region.
References:
1. International Diabetes Foundation. IDF Diabetes Atlas 2014. Brussels: International Diabetes Foundation, 2014.
2. World Health Organisation. Diabetes Programme: About Diabetes (http://www.who.int/diabetes/action_online/basics/en/). Accessed:29/10/2015.
3. World Health Organization. Use of glycated haemoglobin (HbA1c) in the diagnosis of diabetes mellitus: abbreviated report of a WHO consultation. Geneva, World Health Organization: 2011.
4. Beran D. The impact of health systems on diabetes care in low and lower middle income countries. Curr Diab Rep. 2015;15(4):591.
5. Camara A., et al. Poor glycemic control in type 2 diabetes in the South of the Sahara: The issue of limited access to an HbA1c test. Diabetes research and clinical practice. 2015;108(1):187-92.
6. Peer N., et al. Diabetes in the Africa Region: an update. Diabetes Res Clin Pract. 2014;103(2):197-205.
Leave a Reply