Implications of the growing burden of diabetes for premature cardiovascular disease mortality and the attainment of the Sustainable Development Goal target 3.4

Non-communicable diseases (NCDs) are a major cause of deaths globally, and cardiovascular disease (CVD) is the leading cause of these deaths. 42% of NCD deaths are premature (occurring before the age of 70 years). As part of the United Nations 3rd Sustainable Development Goal (SDG) on health and wellbeing, target 3.4 is to reduce premature mortality from NCDs by one third between 2015 and 2030. This target adds to the World Health Organization (WHO) target of reducing premature deaths from NCDs by 25% between 2010 and 2025. As diabetes is a major risk factor for CVD, it is important to account for the trends in diabetes when considering premature CVD mortality. We aimed to describe the global trends in diabetes prevalence and mortality, critically review the literature on the estimated attainability of the WHO and SDG targets, and determine if and how these studies accounted for trends in diabetes. Worldwide, the prevalence of diabetes is rising, with an estimated 9.0% global prevalence in adults aged 20-69 by 2030, and low- and middle-income countries (LIMICs) having the largest increase of the burden in absolute numbers and age-standardized prevalence. There is a lack of data from most LMICs on the excess CVD mortality associated with diabetes and therefore no consensus on the global risk of CVD mortality in people with diabetes. Where data do exist, there are discrepancies between studies on the direction of mortality trends from diabetes over time. We reviewed 12 studies that estimated the attainability of the WHO or SDG targets for premature NCD mortality. Seven of these considered the potential impacts of achieving the 2025 WHO risk factor targets. Six studies modelled the impact of current trends in risk factors, including diabetes, continuing toward the target dates. Four studies compared this 'business as usual' model with the attainment of the risk factor targets for the world as whole and individual regions, 2 studies for NCD mortality overall, and 2 specifically for CVD mortality. On the impact of diabetes with regards to attainment of the WHO or SDG targets for premature CVD mortality, the overall results were inconclusive. Some conduded that none of the countries or regions considered would meet the targets, and others predicted that in some areas, the targets would be met. Examining the potential impact of trends in diabetes on future CVD mortality rates in LMICs is limited by a relative lack of high quality studies, including on the age specific excess mortality associated with diabetes. Filling these data gaps will enable better estimates of the potential impacts on future CVD mortality of the rapidly increasing prevalence of diabetes in LMICs and help to better inform health policy and the attainment of SDG target 3.4.