Impaired fasting glucose more predictive of T2DM than MetS

Impaired fasting glucose (IFG) appears to be a stronger risk factor for type 2 diabetes mellitus (T2DM) than metabolic syndrome (MetS), reports a new Japan study. The coexistence of the two factors confers the highest T2DM risk.

Researchers prospectively followed 4,131 Japanese workers (mean age, 50 years; 3,417 men) who had no prior history of diabetes. IFG was defined as fasting blood glucose 100–125 mg/dL; MetS was defined as abdominal obesity in combination with two or more metabolic risk factors. Fasting blood glucose or glycated haemoglobin, medications, and self-reports were used to determine incident T2DM.

Over a mean follow-up period of 6.3 years, 240 incident cases of T2DM were reported. In those with MetS, the crude incidence rate of T2DM was 20.2 events per 1,000 person-years, as opposed to only 6.1 events per 1,000 person-years in those without MetS. This corresponded to a fully-adjusted hazard ratio (HR) of 3.1 (95 percent confidence interval [CI], 2.3–4.0), suggesting a significant risk excess.

In comparison, the crude rate of T2DM incidence in those with IFG was 29.0 events per 1,000 person-years, similarly greater than that in the no-IFG participants (5.3 events per 1,000 person-years). The corresponding adjusted HR was 4.5 (95 percent CI, 3.4–5.8).

When looking at participants with neither IFG nor MetS, the population attributable fraction (PAF) of T2DM was greater for IFG than it was for MetS (15.6 percent [95 percent CI, 10.1–20.7] vs 9.1 percent [95 percent CI, 3.8–14.2]). The presence of both, however, yielded the highest PAF of 29.7 percent (95 percent CI, 23.0–35.8).