Question from Philadelphia, Pennsylvania, USA:

I am a 26 year old female (5 feet 4 inches tall, 170 pounds) who has a panic disorder. I had elevated blood glucoses in early pregnancy, which I was able to control tightly with minimal insulin, but I miscarried about two months ago. Since then, my levels have been 80-115 mg/dl [4.1-6.4 mmol/L] fasting and up to 170 mg/dl [9.4 mmol/L] at two hours postprandial without medication. Because the spikes were causing visual disturbance, my doctor has me on 850 mg of metformin once daily, and my blood glucose levels are 64-90 mg/dl [3.6-5 mmol/L] fasting and 80-130 mg/dl [4.1-7.2 mmol/L] post-prandial. My diagnoses are gestational diabetes, followed by insulin resistance and impaired glucose tolerance There are several questions, which my doctor doesn’t seem to know the answers to:

How is it possible for metformin to cause low blood glucose? All the literature states that metformin monotherapy never causes hypoglycemia, yet I have frequent lows (40-60 mg/dl [2.3-3.3 mmol/L] which don’t seem to be related to exercise, although a low will follow within an hour of a panic attack. I was also having regular nighttime episodes, marked by sleepwalking and unusual behavior. Ice cream before bed helps but nothing else I’ve tried thus far has worked very well.

How low is “too” low? One of the reputable medical sources I looked at says that hypoglycemia really begins at less than 40 mg/dl [2.2 mmol/L] while other sources recommend treating anything under 90 mg/dl [5 mmol/L] (I suppose on the premise that it could go low. ) At what point does one’s coordination and focus become substantially impaired? I usually feel great until I hit the low 50s mg/dl [2.8 mmol/L], but that’s not a good judgment of my performance.

Would losing weight have had any effect on the metformin? I have lost 34 pounds in about four months, although under the circumstances, it’s hard to tell how it’s affected my control.