Optimal timing for postprandial glucose measurement in pregnant women with diabetes and a non-diabetic pregnant population evaluated by the Continuous Glucose Monitoring System (CGMS).

OBJECTIVE

Using the Continuous Glucose Monitoring System (CGMS; Medtronic Minimed) for a group of pregnant women with and without glucose intolerance, we attempted to answer the following questions: (1) when does the physiological peak of postprandial glucose occur?; (2) do non-diabetic pregnant women and pregnant women with diabetes have different postprandial glucose profiles?; and (3) what is the optimal time for postprandial glucose measurement rated according to clinical outcome?

METHODS

We included 53 pregnant women in our study. Based on the criteria of the German Diabetes Association (fasting, 5.0 mmol/L; 1-h, 10.0 mmol/L; 2-h, 8.6 mmol/L) we included 13 women with gestational diabetes, four with type 1 diabetes and 36 non-diabetic pregnant (NDP) women. Gestational and type 1 diabetics were classed as one group: pregnancy complicated by diabetes (PCD). Patients with carbohydrate intolerance underwent dietary counseling in accordance with the recommendations of the American Diabetes Association. Patients received a CGMS for use over 72 h. This was calibrated seven times a day with an Accu-Check. The pre- and postprandial glucose levels were documented at 15-min intervals for 3 h from the beginning of each meal. The postprandial data from the three meals were added. The group was divided according to three clinical outcome parameters: mode of delivery, birth weight percentile, and diabetes-associated complications.

RESULTS

Statistically significant differences between groups were found for body mass index, fetal birth weight and oral glucose tolerance test. No significant differences were found for age, parity and gestational age, mode of delivery, and diabetes-associated complications. The sensor provided similar numbers of measurements in both groups (278+/-43 vs. 298+/-73, P = 0.507). The postprandial glucose peak was reached after 82+/-18 min in the non-diabetics vs. 74+/-23 min in the PCD group (not significant). Postprandial glucose values were normally slightly higher in PCD (not significant). We added the postprandial glucose values at each time interval for the three meals for each day. For the sum, there was a significant difference between the measurements at 120 min and at 135 min postprandial (P < 0.05). Dividing the group by clinical outcome showed a significant difference between the postprandial time intervals of 75 min and 105 min (P < 0.05). In addition, the time interval was different from 60 min to 135 min for the mode of delivery and birth weight percentile (P < 0.05).

CONCLUSION

The 120-min interval is too long and has a lower correlation to clinical outcome parameters than earlier measurements. Our findings show that the optimal time for testing is between 45 and 120 min postprandial. Based on our practical experience and dietary recommendations, we would prefer a 60-min interval, because patients can calculate this more easily and can have more freedom to eat the recommended number of snacks.