Higher normal range of fasting plasma glucose still has a higher risk for metabolic syndrome: A combined cross-sectional and longitudinal study in elderly

Introduction It is well known that higher fasting plasma glucose (FPG) is associated with metabolic syndrome (MetS). This relationship still exists even the FPG is within the normal range. However, most of these studies did not exclude subjects who were on medications which would affect the results of the studies. At the same time, there is no longitudinal study done to validate this correlation, especially in elderly. In this study, the relationships between normal FPG and MetS were evaluated. Method We randomly selected 57,517 subjects who were ≥ 60-years old from health screening centre. In the first part of study, subjects were enrolled in the cross-sectional study to find out the optimal cut-off value of FPG with higher chances to have MetS. In the second part of current study, subjects with MetS at baseline were excluded from the same study group, and performed a median 5.3-year longitudinal study. Results There were 18,287 subjects enrolled in this study. In the first part of study, the cross-sectional study, optimal cut-off values of FPG were determined by the ROC curve and the sensitivity for these cut-off values were 56.6% in men and 60.9% in women, respectively. The result showed that lower FPG is healthier than the higher (log-rank test, p < 0.001). During the follow-up period, 5039 subjects showed hazard ratios of 2.09 for men and 1.884 for women developing future MetS. Conclusion Our study is the first longitudinal design in elderly and showed that older subjects with higher FPG proved to have higher risk of Mets even the FPG is still within its normal range.