References:
- Dr. RPS Maternal and Newborn Care: A Comprehensive Guide and Source Book for Teaching and Learning, 2nd Edition, ISBN 978-971-98-2265-3, by Rosalinda Parado Salustiano (pp. 117-195)
- Lecturer (V)
The most diabetogenic hormone of pregnancy is Human Placental Lactogen (HPL) from the placenta. HPL production in pregnant women start to increase by the sixth month of pregnancy, the best time for screening for GDM.
Diagnosis
- Glucose Challenge Test (GCT) is the screening test, and requires no special preparations. It involves the administration of 50 grams of glucose solution, and one blood extraction an hour after administration.
- Normal result: <145 mg/dL. If this is exceeded, the client must undergo an oral glucose tolerance test.
- Oral Glucose Tolerance Test (OGTT) is the confirmatory test, and requires two days of increased carbohydrate intake followed by NPO post-midnight the day before the exam. Fasting blood sugar is checked and 100 grams of glucose solution is administered, followed by three consecutive blood extractions one hour, two hours, and three hours after the administration.
- Normal FBS: <90 mg/dL
- Normal result 1 hour after administration: <180 mg/dL
- Normal result 2 hours after administration: <155 mg/dL
- Normal result 3 hours after administration: <145 mg/dL
- If two of the four results are abnormal, GDM is diagnosed. If one is abnormal, a repeat test is done. If only one is still abnormal, GDM is negative.
| Parameter | GCT | OGTT |
|---|---|---|
| Purpose | Screening | Confirmatory |
| Preparation | None | Two days of elevated CHO + Fasting post-midnight |
| Administration | 50 g of glucose solution | 100 g of glucose solution |
| Blood Draws | One, 1 hour after | Four |
| Normal Results | <145 mg/dL | - FBS: <90 mg/dL - 1 hour after: <180 mg/dL - 2 hours after: <155 mg/dL - 3 hours after: <145 mg/dL |
| Follow-up | If abnormal, proceed to OGTT | If 2 of 4 are abnormal, confirmation; if only 1 of 4, repeat. |
Assessment Findings
The classical signs of diabetes are present: polyphagia, polydipsia, polyuria. Polyhydramnios may also occur due to the osmotic effect of glucose.
- Insulin function is blocked by HPL. The hyperglycemia results in fluid shifting
- Polyuria results from increased kidney perfusion as a result of fluid shifting.
- Shrinkage of the cells (cellular dehydration) results in polydipsia
- Cellular starvation results in polyphagia, which may result in further hyperglycemia.
- Cellular starvation leads to initiation of gluconeogenesis, which produces ketone bodies (that accumulate in the brain, resulting in decreased level of consciousness, and urine), resulting in diabetic ketoacidosis, then diabetic coma.
- Ketones may also cross the placenta, absorbed by the fetal blood then body and brain (fetal acidosis), causing permanent cognitive impairment.
- Hyperglycemia results in fetal pancreatic hyperinsulinemia and a macrosomic fetus (>4000 grams) that experiences neonatal hypoglycemia (indicated by jitteriness)
- 40 to 60 mg/dL: normal value
- <40 to <35 mg/dL: assess neonatal sucking ability; if absent, prepare IV Glucose Solution, otherwise, provide oral glucose solution (Oresol)
- 35 mg/dL: IV Glucose Solution
Management
- Diet: diabetic exchange diet, balancing meal proportions to manage glucose levels. The patient must consult with a dietitian.
- Exercise: walking is the best exercise. Prior to the exercise, sustaining carbohydrates are required to prevent sudden hypoglycemia.
- Insulin: two types may be added into one insulin syringe (orange hub).
- Self-administration health education:
- Asepsis; what parts of the syringe not to touch, and how to perform handwashing
- Sites of administration: subcutaneous; upper arm, abdomen, thigh, buttocks in 9 or 12 sites two fingerbreadths away from the umbilicus. avoid injection of insulin in the same site due to lipodystrophy.
- Early delivery may be done for diabetic pregnant women with poor glycemic control. As early as 6 weeks (when surfactant production begins), dexamethasone or betamethasone may be given to improve surfactant production for birth.
| Insulin Type | Examples | Onset | Peak | Duration |
|---|---|---|---|---|
| Short-Acting (Regular, Clear) | Humulin R, Novolin R | 30 minutes - 60 minutes | 2 to 4 hours | 6 to 8 hours |
| Intermediate (Cloudy) | NPH | 2 hours | 6 to 8 hours | 12 to 18 hours |
Mixed Insulin Aspiration
The clear (Regular) insulin is aspirated first to prevent contamination of the short-acting insulin with the long-acting insulin. Contamination of regular with intermediate results in changes in duration, while contamination of intermediate of regular results in changes in onset. Changes in duration results in prolonged hypoglycemia, and is a considerable problem. An earlier onset of intermediate insulin is not a cause of concern.
Provide maternal and fetal monitoring:
- Maternal glucose levels
- Maternal blood pressure
- Maternal weight monitoring
- Ultrasound to detect LGA
- Fetal kick count: normally 5 to 15, average 10.
- Chorionic Villi Sampling for detecting chromosomal defects by week 10 to 12.
- Maternal Serum Alpha-Fetoprotein for detecting chromosomal defects and neural tube defects by week 14 to 16.
- Normal findings: 38 to 42 ng/dL. A deficiency may indicate chromosomal defects, while an excess may indicate neural tube defects.