DRAFT August 2011 Contra Costa Health Services
Dept. Obstetrics and Gynecology
Use of Metformin as an Oral Glucose Lowering Agent during Pregnancy
I. Purpose: To provide guidelines for the Registered Nurse to initiate and adjust metformin dose in consultation with the patient’s primary physician and/or a supervising physician designated by the Obstetrics and Gynecology Department at Contra Costa Regional Medical Center.
II. Circumstances under which the Registered Nurse may perform this function:
A. Setting: Healthy Start Program employed RN with experience or training in GDM/diabetes management in pregnancy.
B. Supervision: Primary physician or medical provider for patient and supervising physician designated by the CCRMC Obstetrics and Gynecology Department.
III. Protocol
A. Definition: This protocol refers to the initiation of and dose adjustment of the oral glucose lowering agent metformin to maintain maternal blood glucose values in the range established by Sweet Success and the CCRMC guidelines for management of diabetes in pregnancy and gestational diabetes.
B. Goals of self-monitoring of blood glucose measurements are as below:
Fasting glucose values <95 gm/dl
One hour after meals < 130 mg/dl
C. Patient who is on metformin at the time of presentation for prenatal care for treatment of elevated glucose measurements should be continued on Metformin by the Healthy Start RN.
C. Contraindications to use of metformin:
Patients with possible contraindications to or a questionable indication for metformin must be discussed with a supervising medical provider before being prescribed metformin.
1. History of renal disease or creatinine known to be > 1.2
2. History of liver disease or abnormal AST or ALT on liver function tests
3. Type I diabetes (history of ketoacidosis)
4. Glucose or HbA1C testing suggesting that the initial treatment should be with insulin, with general guidelines as follows:
A. Fasting blood sugars > 120
B. One hour postprandial glucoses > 200
C. HbA1C > 7.9
*this is particularly important for patients <10 weeks EGA where more rapid control of abnormal blood sugars might lower risk of fetal abnormalities.
5. History of intolerance or allergy to metformin
6. History, physical or lab findings inconsistent with the clinical picture of GDM or diabetes in pregnancy
7. Request of patient, RN, or primary provider
8. Patient on metformin for fertility reasons without elevated blood glucoses prior to pregnancy
D. Monitoring
1. Patients will monitor fasting and one hour post beginning meals (four times per day)
2. Patients will monitor food intake per the current guidelines
3. RN will confirm, usually by assessing the maternal history that erratic blood glucose elevations are NOT caused solely by diet indiscretions that require intervention other than medication. In this case further dietary education should occur before beginning metformin.
E. Indications for Starting Metformin and Increasing Metformin Dose
Metformin should be initiated and increased when persistent glucose elevations (usually after 1-2 weeks of diet/exercise or a lower dose of medication) are as follows:
1. Fasting >90 mg/dL three or more times in a week
2. One hour post meal >130, six or more times in a week
Glucose Abnormality / Start Dose / Timing of Dose / AdjustmentElevated Fasting >95
Normal post meal glucoses / 500 mg / With bedtime snack or with dinner / Increase by 250-500 mg, as tolerated by GI symptoms if goal not attained, no sooner than every 3 days until maximum dose of 1000mg each evening.
Normal fasting values with elevated post meal >130, more than 6 per week. / 500 mg / With breakfast, may increase to divided BID with second dose given with dinner / Increase by 500 mg, as tolerated by GI symptoms until goal attained, not sooner than every 3 days until maximum dose of 2500mg daily, divided BID –TID reached
Both fasting and post meals are elevated / 500 mg daily, increase to 500 mg BID within 3 days / With breakfast and with dinner or bedtime. / Increase to maximum of 2500mg divided BID-TID with increases not sooner than every three days and as tolerated by GI symptoms until postprandial and fasting goals attained. Increase evening dose for elevated fastings and increase morning dose for increased post meal glucoses.
F. Change in Treatment Plan
1. If sugars not adequately controlled on a tolerable amount of Metformin within a reasonable amount of time, usually 2-3 weeks, the primary medical provider or supervising Obstetric Department physician should be contacted to discuss the advisability of instituting insulin or alternate oral treatment. The metformin dose should be continued until a plan to start or add insulin is implemented.
2. The RN should consult liberally with the primary medical provider or supervising Obstetric Department physician whenever there are questions or concerns about the ongoing treatment.