Poor glucose control in women with type 1 diabetes mellitus and 'safe' hemoglobin A1cvalues in the first trimester of pregnancy

OBJECTIVE: To observe glycemic excursions, measured continuously over 24 h, in relation to hemoglobin A1c values in the first trimester of pregnancy of women with type 1 diabetes mellitus. METHODS: The MiniMed Continuous Glucose Monitoring System (CGMS) was used to obtain glucose values every 5 min during 24 h. Hemoglobin A1c was determined at the end of the continuous glucose recording and 6-12 weeks after the continuous glucose recording. RESULTS: Continuous glucose recordings were obtained in 13 women between 7 and 15 weeks of gestation. Nine patients had hemoglobin A1c levels of < or = 7.0% (< 1% above the upper limit of normal range) while up to 41.3% of the readings had values of < 3.9 mmol/l (70 mg/dl) and up to 52.8% of the readings had values of > 7.8 mmol/l (140 mg/dl). CONCLUSIONS: Hemoglobin A1c does not reflect the complexities of glycemic control in women with type 1 diabetes who are considered to have accomplished tight glycemic control in the first trimester of pregnancy.