Data from: Change in fasting plasma glucose and incident type 2 diabetes mellitus: results from a prospective cohort study

Objective: To investigate the association between changes of fasting
plasma glucose (FPG) values and incident type 2 diabetes (T2D) in a cohort
of the Iranian population. Design: Prospective cohort study. Setting: This
study was conducted within the framework of the Tehran Lipid and Glucose
Study (TLGS) to investigate the association between change of FPG between
baseline examination (1999-2001) and the second visit (2002-2005), with
incident T2D. Participants: A total of 3981 non-diabetic participants aged
20 years. Outcome measure: Type 2 diabetes was defined if the participant
was using anti diabetic drugs, or if FPG was ≥ 7mmol L-1 or if the 2-h
post challenge plasma glucose (2-hPCG) was ≥ 11.1 mmol L-1. Results:
During a median follow-up of 6.17 years, after second examination, 288 new
cases of T2D were identified. In the multivariable Cox proportional hazard
analysis using age as timescale, we presented a simple model, including
the FPG change (HR: 1.19, 95% CI: 1.07-1.33) and baseline waist
circumference (WC) (HR: 1.004, 95% CI: 1.001-1.008) with a discriminative
power (C-index) of 72%. Furthermore, we showed that the highest quartile
of FPG change enhanced the T2D risk to 1.65 (95% CI: 1.2-2.27) compared to
the lowest quartile (P for trend=0.004).The independent risk of FPG change
resisted further adjustment with 2-hPCG change. Adding the 2-hPCG change
only, slightly increased the discrimination power of the model, including
FPG change and baseline value of WC (0.73 vs. 0.72 %). After limiting the
study population to those with normal fasting glucose/normal glucose
tolerance, FPG change still remained as an independent predictor (HR :
1.57, 95% CI: 1.31-1.88). Conclusions: Two measurements of FPG obtained
about 3 years apart can help to identify populations at risk for incident
T2D; independent of important traditional risk factors and their changes
including 2-hPCG change.