Brittle diabetes in pregnancy.

In eight brittle diabetics the insulin requirement increased during successful pregnancies from 35 to 64 U./day (in 29 stable severe diabetics from 53 to 78 U./day). The within-day glycemic excursions were calculated as the mean of the three differences between four time points: fasting, one hour after breakfast, two hours after breakfast, and two hours after lunch. This parameter was constant throughout the pregnancy in nondiabetics (34-46 mg./100 ml.) and stable severe diabetics (55-72 mg./100 ml.). In brittle diabetics it dropped from 147 mg./100 ml. before the pregnancy and 153 mg./ 100 ml. at eight weeks to 85 mg./100 ml. at 36 weeks. The between-day variability was calculated as the mean glycemic difference between two successive days at the four points of time noted above. It was very low in nondiabetics (49-53 mg./100 ml.). In brittle diabetics it decreased from 127 mg./100 ml. before pregnancy and 120 mg./100 ml. at eight weeks to 46-55 mg./100 ml. at 24-36 weeks. This shows that brittleness substantially decreased in the second half of pregnancy.