My obstetrician’s office called to say that I failed my one hour glucose screen at 26 weeks gestation and they needed to run the three hour test. When I inquired about the actual numbers, my one hour “score” was 128 mg/dl [7.1 mmol/L] and the practice uses a cut-off of 126 mg/dl [7.0 mmol/L]. Can you explain why the practice would use such a low cut-off value when my research has given cut-off values of 130 mg/dl [7.2 mmol/L] or 140 mg/dl [7.8 mmol/L]? The cut-off values for their three hour test are lower than published as well — 86 mg/dl [4.8 mmol/L] for fasting, and 165 mg/dl [9.2 mmol/L] for one hour. I cannot remember the remaining to values. At this point, the stress of worrying about gestational diabetes based on what I perceive as borderline results seems more of a problem than gestational diabetes itself.

I do not know why your obstetrician is using such a low threshold value for the one hour glucose test. Technically, you had a normal result. I use 130 mg/dl [7.2 mmol/L] in my office. The current recommended three hour test values are fasting less than 95 mg/dl [5.3 mmol/L], one hour less than 180 mg/dl [10.0 mmol/L], two hour less than 155 mg/dl [8.6 mmol/L] and three hour less than 140 mg/dl [7.8 mmol/L]. A compromise would be to check a fasting, pre-meal and one hour post-meal glucose values for a few days. Your fasting glucose should be 70 mg/dl [3.9 mmol/L] to 90 mg/dl [5.0 mmol/L], pre-meal less than 100 mg/dl [5.6 mmol/L] and one hour post-meal less than 130 mg/dl [7.2 mmol/L]. If you want, you can reference the ACOG Practice Bulletin, Number 30, September 2001. This is in the 2006 Compendium of Selected Publications from the American College of Obstetricians and Gynecologists.

OWJ