Short summary

The purpose is: 1. IDENTIFY the prevalence of T2D in Guinea-Bissau; 2. ASSESS a novel prevention for T2D, using the BCG vaccine, by performing a randomized trial in pre-diabetes inviduals and measuring metabolic markers, (glucose, HbA1c, insulin, leptin and adiponectin), and relating with inflammatory markers (interleukin (IL)-6, IL-10, IL-33, TGFb, TNFa) pre- and post-trial; and 3. REDUCE the diabetes burden by health education, capacity building and community engagement accross the country.

Rationale

Recent epidemiological studies have shown that the BCG vaccine, given against tuberculosis (TB), has important non-specific effects. It reduces mortality to a much larger extent than what can be ascribed to prevention of TB infection alone. Recent immunological studies have pointed to a likely mechanism: BCG vaccination increases basal systemic levels of type 1 cytokines and immune cells and it can induces epigenetic modifications in the innate immun cells, e.g. monocytes and NK cells, leading to increased pro-nflammatory responses towards unrelated pathogens. These modifications are accompanied by changes in glucose metabolism, increasing aerobic glycolysis, a state of high glucose utilization.

In the US, a recent long-term follow-up of a randomized trial seeking to use BCG as a treatment of T1D, it was discovered that two doses of BCG, given 4 weeks apart to patients with T1D, BCG lowered HbA1c close to normal levels. Corroborating the observations from other studies, a systemic shift in glucose metabolism from oxidative phosphorylation to aerobic glycolysis was observed and confirmed by metabolomics, and functional assays of cellular glucose uptake after BCG vaccinations. If these findings are correct, BCG vaccination could be a cheap and safe tool to prevent and treat not only T1D but also T2D, in parts of the world were patients cannot afford medication.

In Sub-Saharan Africa, the prevalence of diabetes has increased rapidly over the past decades. In Guinea-Bissau only a couple of small diabetes studies have been performed in patients with tuberculosis and HIV. More recently, an important study was performed in the country which identified the severe lack of diabetes prevention, management and education. This study has indicated a complete lack of resources, including no endocrinologist or diabetes trained doctors and nurses and no significant training of general health professionals. Most importantly, the study further indicates the lack of awareness about diabetes in the general population, including within the medical staff. There are no standardized care protocols for diagnosis and treatment of diabetes, or follow up for those few that have been diagnosed. Moreover, in a recent study, the mortality among T2D patients was found to be high and death caused by bacterial infections, including in those with the diabetic foot (DFU) is very common. BCG vaccination would thus be a very valuable tool to treat diabetes in countries like Guinea Bissau in Sub-Saharan Africa.

It is difficult to overstate the need for a better understanding of the pathophysiology of T2D in order to develop effective preventive and treatment strategies to improve the lives of people with the disease. Diabetes is one of the non-communicable diseases that has become a global burden. Subjects with T2D are at much higher risk of developing severe complications from COVID- 19 infection. T2D is one of the leading causes of disability-adjusted life-years in adults.

In this study, we therefore aim to: 1. IDENTIFY the T2D incidence; 2. ASSESS a novel treatment strategy (BCG vaccination) for T2D in order to manage the disease and link metabolic dysfunction with inflammatory profiles. Last but not least, 3. REDUCE the national diabetes burden by capacity building, educating and teaching, through strong collaborative networks of community engagement through local stakeholders, in Guinea- Bissau, involved in the project and those outside the country, from Portugal and Denmark.

Description of the cohort

The study has four aims:

Aim 1) Establish the Type-2 diabetes (T2D) prevalence, by measuring the T2D and pre-diabetes incidence in six centers around the country. This will be done using fasting blood glucose and hba1c for selected subjects. A biobank will be established. In total 2200 inviduals will be screened in this group, with an expected participation rate of 90%.

Aim 2) Assess the impact of culture and environment on T2D incidence by quantitative medical anthropology surveys and interviews.

Aim 3) Conduct a randomized trial to investigate the metabolic effects of two BCG vaccinations 4 weeks apart in newly diagnosed prediabetic subjects. Metabolic status is monitored by measuring metabolic markers and relating these with inflammatory markers pre and post-trial. A biobank will be established here as well. The trial will include a total of 150 individuals with pre-diabetes.

Aim 4) Create a strong capacity building and educational collaborative network through community engagement.

Data and biological material

The collected data will include demographic data, as well as clinical data regarding blood glucose levels, height, weight, BMI, as well as hba1c and other biomarkers as specified in the protocol. The biomarkers (for metabolic analyses) will be analysed at the Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.

Collaborating researchers and departments

Department of Epidemiology, Steno Diabetes Center Copenhagen,

• Stine Byberg

Center for Neuroscience and Cell Biology, University of Coimbra, Portugal

• Eugenia Carvalho

Bandim Health Project, Guinea-Bissau

• Lilica Sanca