Research on Helicobacter pylori (H. pylori), a pathogenic bacterium that is widespread among humans, is investigating the medical implications of the infection in many fields beyond gastroenterology. Because of the ubiquitous presence of the infection, there is an increasing interest in finding a relationship between this bacterium and diabetes mellitus (DM). It is not clear whether a significant relation between H. pylori and DM exists, whether the infection influences diabetes or vice versa, and the mechanisms underlying such a relationship. This review provides an analysis of new insights from studies published in more recent years. New research on this topic concentrated on the common pathogenic aspects between the bacterium and insulin resistance or autoimmunity, on the role of the bacterial infection in cardiovascular risk and whether the infection worsen glycemic outcomes in patients with DM. Research in this field still has to conclusively assess and explain the existence of a possible relationship between H. pylori and DM. Some studies have reached antithetic conclusions. Unless more robust data from studies using consistent research methods become available in the near future, people with diabetes should be compared to the general population when it comes to investigating and treating the presence of H. pylori.