"Results
COVID-19 vaccine aggravates insulin resistance in diabetic patients
We first conducted a longitudinal clinical trial to determine the effects of the COVID-19 vaccine in healthy controls, pre-diabetic subjects, and diabetic subjects. Between 1 June 2023 and 31 October 2023, we recruited 155 adults who have received two doses of the mRNA 80 COVID-19 vaccine (BNT162b2)... Human volunteers were recruited to determine their immune responses and glucose control before and 2 weeks after the booster...
[W]e found exacerbated risks of glucose intolerance and insulin resistance after the booster shots of COVID-19 mRNA vaccination in pre-diabetic patients and diabetic patients, as revealed by the significant elevation of HbA1c, homeostatic model assessment for insulin resistance (HOMA-IR), triglyceride (TG) and triglyceride-glucose index (TyG)... About 61.1% of diabetic subjects had impairment of insulin sensitivity according to the HOMA-IR index and about 66.7% of diabetic subjects had increased risks of cardiovascular complications according to the TyG index. Moreover, correlation analysis revealed HOMA-IR index is positively correlated with a series of immune responses including SARS-CoV-2 spike protein, SARS-CoV-2 spike (Trimer) IgG, and neutralizing abilities of SARS-CoV-2 protein after COVID-19 vaccination (p<0.05 in all cases, r=0.2162, 0.2102 and 0.2746, Figure.1J-L). These results suggest that the booster shot of mRNA COVID-19 vaccine impairs glucose control and aggravates insulin resistance in human subjects with type 2 diabetes...
COVID-19 vaccine impairs insulin signaling in mice
To study the inhibitory action of COVID-19 vaccination on glucose control, we first performed a glucose tolerance test in healthy mice that received mRNA COVID-19 vaccine (BNT162b2) weekly. Compared to mice treated with saline, mice treated with the COVID-19 vaccine exhibited immune responses similar as shown by the elevation of SARS-CoV-2 spike protein in serum (p=0.001, Figure.2A). Interestingly, we showed mice after the fourth dose of COVID114 19 vaccine exhibited impaired glucose tolerance examined by oral glucose tolerance test (OGTT) (p<0.05 in all cases, Figure.2B-C). We also showed serum triglyceride, but not FBG, serum insulin level or bodyweight, is significantly elevated in mice with weekly COVID-19 vaccination (p=0.0305 for Figure.2D, n.s. for Figure.2E-G), indicating an increased risk of cardiovascular diseases and metabolic disorders. Coupled with impaired glucose tolerance, the reduction in blood glucose in response to insulin challenge in the insulin tolerance test (ITT) (p<0.05 in all case, Figure.2H-I) and the level of insulin-induced Akt phosphorylation in insulin-sensitive tissues were significantly reduced in mice with COVID-19 vaccination (p<0.05 in all cases, Figure.2J-M). These results suggested that the glucose intolerance induced by the COVID-19 vaccine is mediated by impairment of insulin sensitivity rather than impaired insulin secretion in mice."
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