October 14, 2003
Question from Dallas, Texas, USA:
I am currently 28 weeks pregnant and had the blood glucose test done this past week but I have not received the results yet. I used my husband’s glucose meter to check the other day because I wasn’t feeling well, and I think it was high (159 mg/dl [8.8 mmol/L] one hour after eating). What are normal blood sugar levels should be for someone without gestational diabetes? When is the best time and way to check myself?
There is some variation on the criteria for a one hour glucose screening test, but the value I use is less than 135mg/dl [7.5 mmol/L]. If you exceed this value, then it is necessary to do a three-hour test. The criteria are fasting less than 95 mg/dl [5.3 mmol/L], one hour less than 180 mg/dl [10 mmol/L], two-hour less than 155 mg/dl [8.6 mmol/L], three-hour less than 140 mg/dl [7.8 mmol/L]. Morning fasting glucose should be 70-90 mg/dl [3.9-5 mmol/L], and one hour after a meal it should less than 130 mg/dl [7.2 mmol/L] or less than 120 mg/dl [6.7 mmol/L] at two hours. Thus, your value of 159 mg/dl [8.8 mmol/L] is certainly concerning. However, it takes formal testing to make a diagnosis of gestational diabetes. The usual times for testing are upon waking in the morning and just before and either one or two hours after meals.