Effectiveness and safety of COVID-19 vaccines in patients with diabetes as a factor for vaccine hesitancy

Table 1 Existing studies on effectiveness of coronavirus disease 2019 vaccines in patients with diabetes

Ref.	Type of study	Type and name of the vaccine	Participants	Efficacy/effectiveness	Adverse effects
Nomura et al[63]	Observational study	BNT162b2	12 from a total of 252, at a mean age of 43.9 yr	Lower antibody titers compared to non-diabetic subjects 3 mo post-vaccination	N/A
Lustig et al[64]	Longitudinal cohort study	BNT162b2	139 from a total of 2498, at a mean age of 47.7 yr; mostly healthcare workers	Substantial antibody response after 2 doses, but overall lower concentrations of IgG and IgA in diabetics compared to healthy adults	N/A
Van Praet et al[65]	Case-control study	BNT162b2	25 from a total of 75, at a mean age of 85 yr	Decreased cellular immune response only in individuals with diabetes or active malignancy in the studied population	N/A
Ali et al[66]	Cohort study	BNT162b2	81	The BNT162b2 vaccine induced robust IgG and neutralizing antibody responses in people with and without T2DM. On average, diabetics had 13.86 BAU/mL less IgG and 4.42% less neutralizing antibodies compared to non-diabetics	N/A
Marfella et al[67]	Prospective observational study	BNT162b2, mRNA-1273, ChAdOx1-S	251, of which 134 with optimal glycemic control and 117 with poor glycemic control	21 d after the second dose, neutralizing antibody titers and CD4 Th1 cytokine responses were weaker in individuals with HbA1c > 7% compared to those with HbA1c < 7% whose titers were indistinguishable from those of healthy subjects	N/A
Singh et al[68]	Cross-sectional study	ChAdOx1-nCOV (Covishield), BBV-152 (Covaxin)	52 from a total of 463 at a mean age of 44.8 yr	Amongst all studied comorbidities, people with T2DM had lower seropositivity rates compared to those without (84.6% vs 96.1%)	N/A
Sauré et al[69]	Surveillance study	CoronaVac, BNT162b2	4626 from a total of 59987 people from Chile’s population	IgG seropositivity was significantly lower in diabetics receiving the CoronaVac vaccine compared to healthy subjects	N/A
Piccini et al[70]	Retrospective cohort study	mRNA-1273BNT162b2	39	In adolescents and young adults with T1DM, vaccination with either product was safe and did not influence glycemic control	No serious adverse events were reported
Watanabe et al[71]	Observational study	Pfizer/BioNTech BNT162b2 vaccine	2 from a total of 66 at a mean age of 29 yr; mostly healthcare workers	Undetectable titers of anti-SARS-CoV-2 antibodies	N/A
Karamese and Tutuncu[72]	Cross-sectional study	CoronaVac	49 from a total of 186 people, at a mean age of 70.4 yr	Significantly lower levels of anti-SARS-CoV-2 antibodies in diabetes patients than in the controls	N/A

SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2; IgG: Immunoglobulin G; T1DM: Type 1 diabetes mellitus; T2DM: Type 2 diabetes mellitus; N/A: Not applicable; BAU: Binding antibody units.