Relationship between blood glucose level and mortality in Type 2 diabetes mellitus: a systematic review

Aim. To review the relationship between blood glucose level and mortality in patients with Type 2 diabetes mellitus (DM) as reported in the literature. Methods. Literature search using Medline Search: January 1966 - April 1998. Keywords: Diabetes, Non Insulin Dependent, Mortality. Inclusion criteria for papers were: Type 2 DM; follow-up for at least 3 years; glucose or glycated haemoglobin (HbA(1C)) was used as parameter; published in the form of an article. Additionally all references in the selected articles that dealt with the relationship between blood glucose level and mortality in Type 2 DM were included in the search. Results. Twenty-seven eligible articles were found. Twenty-three of them showed a positive association: measures of elevated blood glucose concentrations were associated with higher mortality; in 15 out of 23 studies the positive association was statistically significant, in two only for postprandial blood glucose. One study found a nonsignificant negative relationship in a very old population. Conclusion. In the literature there is a positive, but rather weak, association between the measures of blood glucose control and the risk of dying of patients with Type 2 DM. In the six larger studies (more than 100 deceased patients) that used a continuous categorization of glycaemia, the Risk ratio per unit varies from 1.03 to 1.12.