Association of serum glycine levels with metabolic syndrome in an elderly Chinese population

Background Several studies have identified a negative association between serum glycine (Gly) levels and metabolic syndrome (MetS). However, this association has not been fully established in the elderly. Methods A total of 472 Chinese individuals (272 males and 200 females, 70.1 ± 6.6 years old) participated in a population-based, cross-sectional survey in Beijing Hospital. The MetS and its components were defined based on the 2006 International Diabetes Federation (IDF) standard for Asians. Serum Gly concentration was determined using isotope dilution liquid chromatography tandem mass spectrometry. Result The proportion of patients with MetS decreased gradually with increasing Gly levels ( p for trend < 0.001), and serum Gly concentrations declined gradually with increasing numbers of MetS components ( p = 0.03 for trend). After adjusting for age and gender, lower Gly levels were significantly associated with MetS and central obesity, with OR (95% CI) of 0.40 (0.25–0.65) and 0.46 (0.28–0.74). The stratified analysis conducted according to age showed that the OR between serum Gly levels and MetS was greater in those older than 65 (OR = 0.66; 95% CI, 0.51–0.86) than in those younger than 65 (OR = 0.89; 95% CI, 0.54–1.46). In the stratified analysis, using other age cut-off points, the results consistently showed that the association between serum Gly levels and MetS was more remarkable in the older groups. Conclusions Gly levels are associated with cardiometabolic characteristics and MetS in the elderly, and the association is more pronounced in very old people than in younger old people.