Casual serum triglyceride as a predictor of premature type 2 diabetes mellitus: an 8-year cohort study of middle-aged Japanese workers

Background: The utility of casual serum triglyceride (TG) as a predictor of type 2 diabetes mellitus (DM) is unclear, especially during the most productive years. Methods: Participants were 3271 workers (913 men and 2358 women, age 20–57) without DM at baseline. They underwent consecutive annual medical check-ups for 8 years. The association between newly diagnosed DM and casual serum TG level was determined by classifying the participants into 4 groups according to casual serum TG level at baseline: below 50 mg/dL (group A), 50–100 mg/dL (group B), 100–150 mg/dL (group C), and ≥150 mg/dL (group D). The effects of casual serum TG level in combination with sex, obesity, or serum glucose level on newly diagnosed DM were also evaluated. Results: A total of 222 newly diagnosed type 2 DM cases with a mean age of 50 years old were observed during the follow-up period, i.e., 10/406 in group A, 66/1534 in group B, 58/712 in group C, and 88/619 in group D. Compared with group A, the odds ratio (ORs) for newly diagnosed DM (after adjusting for DM-associated factors) was found to increase with casual serum TG level: 1.38 (group B), 1.79 (group C), and 2.36 (group D). Moreover, the OR for newly diagnosed DM was higher in participants with high casual serum TG levels who were also male (OR 2.46), obese (OR 4.18), or had a high serum glucose level (OR 6.96) than in the reference group. Conclusions: Serum TG level ≥150 mg/dL when fasting or nonfasting is a significant predictor of type 2 diabetes in middle-aged Japanese workers.