PRAGUE — Normative values for mean blood glucose levels during the first trimester may be much lower than what has been reported previously, Dr. Yariv Yogev reported at the 20th European Congress of Perinatal Medicine.
This lower-than-expected glycemic profile may suggest new targets for glycemic control during pregnancy complicated by diabetes, said Dr. Yogev of the department of obstetrics and gynecology at Rabin Medical Center, Petah Tikva, Israel.
Before this study, there was little information on the definition of normal blood glucose levels during pregnancy, especially during the first trimester, he said. Most of the previous information had come from “very limited studies” of 10–25 patients, mostly in the third trimester, who were placed on a strict diet and hospitalized to evaluate their glycemic profile.
The current study included 62 healthy, nondiabetic women in their first trimester of pregnancy (average of 10 weeks' gestation). The investigators fit the women with continuous glucose monitoring devices that measured their blood glucose levels every 5 minutes for 72 hours. Patients were asked not to modify their lifestyles or nutritional habits.
Because of the difficulty of performing continuous glucose monitoring in nondiabetic women with a normal pregnancy, the study did not involve a specific cohort of patients but instead mostly included doctors' wives, midwives, and nurses.
The women's overall mean blood glucose (79.3 mg/dL) and mean fasting blood glucose levels (75 mg/dL) were “much, much lower than was previously reported by others” Dr. Yogev said.
Mean nighttime blood glucose levels (66 mg/dL) “almost represented hypoglycemia,” but such values may actually represent “normal physiology during the first trimester in nondiabetic patients,” he said.
The postprandial glycemic profile of the women was the same after each meal. Mean blood glucose values started at 79 mg/dL just before a meal and rose to 106 mg/dL 60 minutes after the meal; it reached a high of 112 mg/dL 74 minutes after the meal. The values reached 99 mg/dL at 2 hours and 82 mg/dL at 3 hours.
The fasting and overall mean blood glucose levels were similar in 18 obese (defined as a body mass index greater than 27.3 kg/m
The obese patients were characterized by a higher postprandial peak value, a longer time interval to reach the postprandial peak value, and higher mean blood glucose levels during the 3 hours after each meal, Dr. Yogev said.