Question from Honolulu, Hawaii, USA:

I had gestational diabetes with my previous pregnancy and almost had to go on insulin. My level after a one hour Glucola test was 214 mg/dl [11.9 mmol/L]. Luckily, since I work out almost every day and am knowledgeable about what foods to eat, I was able to control it through diet.

That said, I am now 33 weeks pregnant with my second baby and have been watching my diet from the start. At 28 weeks, my first Glucola test came out a little high 50 ml, 168mg/dl [9.3 mmol/L]. They gave me a glucometer to use since I was going on a two week trip and wasn’t able to do a three hour test before that time. Ever since then, I have been testing myself four times a day. My fasting levels are always too high, anywhere around 110 mg/dl [6.1 mmol/L]. The other levels I am usually able to control by diet and exercise. My OB doctor told me to get my fasting levels down, otherwise, I would have to go on insulin, but still wanted me to do the three hour test, so I did.

That morning, according to my glucometer, my levels where: fasting — 116 mg/dl [6.4 mmol/L]; after 1 hour 100 ml Glucola — 224/mg/dl [12.4 mmol/L]; two hours — 168 mg/dl [9.3 mmol/L]; and, at the three hour point, 71 mg/dl [3.9 mmol/L]. The gentleman at the laboratory also took my fasting test and told me his reading also came out to 116 mg/dl [6.4 mmol/L](from the vein in my arm).

Two days later, I got a call from my doctor telling me that my test came out fine. One hour — 168 mg/dl [9.3 mmol/L]; two hours — 135mg/dl [7.5 mmol/L]; and three hours 61 mg/dl [3.4 mmol/L]. When he read me my readings, and knowing my body very well, I seriously thought that he had the wrong results in front of him. My fasting levels continue to be too high and, if I don’t stick to my diet, my sugar levels are above the normal range.

Is there that much difference in a glucometer reading and a venipuncture laboratory reading? I’m confused because, according to my glucometer, I would have to go on insulin. Should I get an second opinion?