Post-Prandial Plasma Glucose Less Than or Equal to 70 mg/dL Is Not Uncommon in Young Japanese Women

BACKGROUND Post-breakfast/post-challenge plasma glucose (PG) concentrations were studied less in young normal weight Japanese women. We addressed these issues. METHODS Two separate groups of female collegiate athletes and female untrained students underwent either a standardized meal test or a standard 75-g oral glucose tolerance test, but not both. Frequency of women whose post-breakfast/post-load PG fell to 70 mg/dL or lower (termed as low glycemia) was compared between athletes and non-athletes, who also underwent measurements of serum adipokines, markers of insulin resistance and inflammation and dual-energy X-ray absorptiometry. Insulin secretion, insulin sensitivity/resistance and serum adipokines were compared between women with and without post-breakfast low glycemia. The same comparison was done between women whose post-breakfast PG returned to levels below the fasting PG and women whose post-breakfast PG never fell below the fasting PG. RESULTS There was no difference between athletes and non-athletes in frequency of post-breakfast low glycemia (47% (8/17) and 44% (8/18)) and post-challenge low glycemia (24% (12/50) and 23% (27/118)). As compared to seven women whose post-breakfast PG never fell below the fasting PG, 28 women whose post-breakfast PG returned to levels below the fasting PG had higher meal-induced insulin responses (283 ± 366 vs. 89 ± 36 µU/mg, P = 0.014). However, two groups did not differ in body composition, markers of insulin resistance and serum adiponectin. No significant difference was also observed in any of these variables between women with and without post-breakfast low glycemia. CONCLUSION Post-prandial PG ≤ 70 mg/dL is not uncommon in young normal weight Japanese women and may not be a pathological condition. The underlying mechanisms for this finding need further exploration.