Surajit Chakraborty, Ankur Mittal and Dibyajyoti Banerjee*
Background: In advanced diabetes mellitus, incidences of infections are high, but insulin concentration tends to decline. However, in conditions associated with the prediabetes (like obesity etc.) incidence of infections are also reported to be high, but there is marked hyperinsulinemia. Therefore, evidence is documented in the scientific literature that both in hypo and hyperinsulinemic conditions infections are prevalent. To the best of our knowledge, the effect of insulin per se on bacterial growth is not worked out. With this background information, we feel that it is important to know about the effect of insulin on bacterial growth. Aim of the study: The aim of the study is to investigate the effect of human recombinant insulin on bacterial growth. Methods: A few mycobacterial species, Escherichia coli, and Staphylococcus aureus were grown in appropriate media in presence and absence of human recombinant insulin and growth assessment was done by standard procedure. Results: It was observed that supraphysiological concentrations of insulin are supporting the growth of the tested mycobacterial species, Escherichia coli, and Staphylococcus aureus with respect to appropriate m-cresol control. For Escherichia coli and Staphylococcus aureus, bacterial growth was observed to be supported by insulin in nutrient media which does not contain glucose. The physiological concentration of insulin has not shown any evidence of supporting bacterial growth under chosen experimental conditions. Conclusion: From the observations documented in this study, we conclude that human recombinant insulin supports the growth of some mycobacterial species, Escherichia coli, and Staphylococcus aureus in glucose independent manner.