The effect of glycaemic control on neutralizing antibody response to COVID-19 among patients with type 2 diabetes mellitus in the Kurunegala district of Sri Lanka; A prospective cohort study

Abstract

BACKGROUND: The antibody response following COVID-19 vaccination among patients with diabetes mellitus (DM) is of particular concern given the increased risk of severe disease in this population. The correlation between glycaemic control among persons with DM and the antibody response was not published in Asian populations. Hence, this study aimed to determine whether glycaemic control has an association with the development of an adequate antibody response for SARS-CoV-2 among patients with DM following the administration of two doses of the COVID-19 vaccine. METHODS: A prospective cohort study was carried out at three vaccination centers in the Kurunegala district from November 2021 to January 2022. Seventy-one patients with type 2 diabetes were recruited for this study and followed up on vaccination with the Sinopharm COVID-19 vaccine. HbA1 c levels at the first dose and after 6-8 weeks from the second dose of vaccine were analyzed. The neutralizing antibodies (NAbs) were analyzed using C Pass™ neutralizing antibody detection ELISA Kit following 6-8 weeks of the 2nd dose. RESULTS: The median (IQR) age of the total population (63.4% females) was 53 years (44.0-58.0) and they were diagnosed with diabetes for 6 years (3-11 years). The median first and second HbAlc values were 9.3% (7.2-10.7%) and 8.2% (7.1-10.2%) respectively. From the total population, only 66.2% developed protective levels of NAbs after 6-8 weeks of the second dose of the vaccine. The second HbAlc value was significantly lower compared to the first (z=-2.63, p=0.008). There was no significant difference in terms of sex, age, duration of diabetes, pre-vaccination HbAlc level, or HbAlc level 6-8 weeks after the vaccination among those who developed protective levels of antibodies and those who did not (p>0.05). There was no difference in sero-conversion depending on the abnormal HbAlc value (.28%) (1st HbAlc p=0.957, 2nd HbAlc p=0.360). Conclusion: We did not detect an association between glycaemic control and sero-conversion. However, 1/3rd of patients with diabetes did not have a protective level of NAbs following 2 doses of Sinopharm COVID-19 vaccination. Furthermore, glycaemic control did not deteriorate with COVID-19 vaccination.