Table 1.

Search strategy.

Objectives	(i)To assess the contribution of existing literature of association of electronic cigarette use and metabolic syndrome development as well as its individual components (insulin resistance, diabetes, dyslipidemia, obesity, blood pressure). (ii)To compare the impact of e-cigarettes use and smoking conventional cigarettes on metabolic syndrome (iii)To identify relevant information and outline existing knowledge (iv)To identify any gap in the existing research
Research question	(i)Does electronic cigarette use have a significant impact on metabolic syndrome development? (ii)Does electronic cigarette use have a significant impact on the occurrence of metabolic syndrome components (insulin resistance, diabetes, dyslipidemia, obesity, blood pressure)?
Keywords	(i)“electronic cigarettes” or “tobacco smoking” and “metabolic syndrome”; (ii)“electronic cigarettes” or “tobacco smoking” and “insulin resistance”; (iii)“electronic cigarettes” or “tobacco smoking” and “diabetes”; (iv)“electronic cigarettes” or “tobacco smoking” and “dyslipidemia”; (v)“electronic cigarettes” or “tobacco smoking” and “obesity”; (vi)“electronic cigarettes” or “tobacco smoking” and “blood pressure”