Aims: The evidence base for fasting plasma glucose (FPG) in the non-diabetic range as a risk factor for cardiovascular disease (CVD) is inconclusive. We investigated this question in the West of Scotland Coronary Prevention Study (WOSCOPS).
Methods and results: In WOSCOPS, we related FPG in 6447 men (mean age 55 years) with hypercholesterolaemia, but no history of CVD or diabetes, to the risk of cardiovascular events and mortality over 14.7 years of follow-up; 2381 non-fatal/fatal cardiovascular events and 1244 deaths occurred. Participants were divided into fifths of baseline FPG, Q1 (< or =4.3 mmol/L) to Q5 (>5.1-6.9 mmol/L). Q2 was designated the referent based on previous studies which have suggested a J-shaped relationship between FPG and CVD. Compared with Q2 (>4.3-4.6 mmol/L), men in Q5 had no elevated risk for cardiovascular events [hazard ratio (HR) 0.95 (0.83-1.08)], or all-cause mortality [HR 0.96 (0.80-1.15)] in fully adjusted analyses despite a significant risk for incident diabetes [HR 22.05 (10.75-45.22)]. After further dividing Q5 into fifths, Q5a-e, individuals in Q5e (FPG 5.8-6.9 mmol/L) were also not at increased risk of cardiovascular events [HR 1.05 (0.82-1.35)] or other endpoints compared with Q2. All results were similar using Q1 as the referent.
Conclusion: Elevations in FPG in the non-diabetic range were not associated with long-term risk of cardiovascular events in middle-aged men in WOSCOPS. These data suggest that the current FPG cutoff for diagnosing diabetes also appropriately identifies western men at risk of CVD.