Earlier studies and reviews have shown an association between high fasting blood glucose levels (FBG) and increased mortality. Less is known about the association between low FBG and mortality. This study aimed at reviewing the literature on this topic. A search was performed primarily of Medline through PubMed, and secondarily by searching other databases and using the information from articles already found. Altogether 5 articles meeting the quality demands of the search were found, all supporting the association between low FBG and increased all-cause mortality, with multivariate adjusted hazard ratios between 1.2 and 3.2. Another 22 articles not fulfilling the quality criteria were studied, and actually no study contradicted this association. Most studies were focused on the relation between high FBG and mortality, and did not analyze the association between low FBG and mortality specifically, hence explaining the low number of conclusive articles focusing on this. Thus we conclude, that low FBG is associated with increased mortality, but the cause of this association is unclear. We hypothesize, that low FBG could be a marker of low fat-free mass and low nutrition intake. This topic needs further studies.