Effect of mRNA Covid-19 Vaccines on Blood Glucose Levels in People with Type I or Type II Diabetes

Abstract

Background: People with diabetes are at increased risk for complications from COVID-19 infection and are encouraged to get vaccinated. However, it has yet to be determined how mRNA vaccines affect blood glucose in people with Diabetes. The purpose of our study was to determine if people with Type I or Type II Diabetes developed a significant change in blood glucose as reported on Continuous Glucose Monitoring (CGM) devices within one week after receiving each dose of an mRNA vaccine. Methods: An IRB approved, retrospective review of 25 subjects data was obtained using their Dexcom® or FreeStyle Libre® CGM from 12/2020–05/2021. For seven days following each dose and seven days immediately preceding the dose (control), average, peak daily, peak postprandial, and fasting glucose was collected. Visual analog symptom scales estimated severity of symptoms following each vaccine dose. Age, BMI and concurrent medications were noted. Descriptive statistics, analyses of differences, mixed effects models and generalized estimating equations were used. Tests were two-tailed and a p value < 0.05 denoted statistical significance. Results: Median age was 75 years, with 76% male and average BMI of 29.5kg/m2. Before and after administration of each dose, significant increases were found in average daily glucose (154 vs 159, p<0.0001), peak glucose after breakfast (183 vs 190,p= 0.0159), after lunch (185 vs 203, p = 0.0002), after dinner (194 vs 204, p = 0.003,) and fasting daily glucose (137 vs 146, p = 0.0144,). There was a significant increase in average glucose levels (156 vs 167, p = 0.0185) following vaccination in the sixteen participants with side effects. There was also a direct correlation between usage of basal insulin and rise in average glucose following vaccination (p < 0 .0001). Conclusion: In a small group of subjects with diabetes, we have shown that mRNA COVID-19 vaccination results in modest, temporary elevations to average, peak and fasting glucoses for up to 1 week. Additionally, we found that changes in average daily blood glucose may correlate with the presence of side effects. Our findings help raise awareness of transient hyperglycemia and the need for more vigilant glucose monitoring following vaccination.