Pocket ObGyn – Diabetes in Pregnancy / Gestational Diabetes
See Abbreviations
Epidemiology
- Pregestational diabetes in ~1% of all pregnancies, mostly type II.
- 90% of diabetes in Preg is GDM (see GDM, below)
Clinical Manifestation
- Type I usually known prior to Type II may have been unrecognized, but if gluc intolerance before 20 w, consider pregestational. Goal preconception HgA1c <6.5%. Consider hospital admission for very poor control during organogenesis.
- Fetal malformation rate in a nml Preg is 2–3% 6–12% in pregnancies c/b diabetes (Obstet Gynecol 2003;102:857). Rate of fetal malformations w/ Hgb A1c 7–8.9 = 5–10%; Hbg A1c 9–10.9 = 10–20%, HbgA1c >11 = >20%
- “Usual” defects include cardiac, renal, neural Esp double outlet RV, truncus arteriosus, & caudal regression syn/sacral agenesis (considered pathognomonic).
- Risks of DM in Preg: malformations, SAB, IUGR, progression of nephropathy, retinopathy, cardiovascular dz, polyhydramnios, preeclampsia, labor dystocia & C/S deliv, fetal macrosomia, lacerations, shoulder dystocia, neonat RDS/hypoglycemia.
| White classification of diabetes mellitus | |||
| Gestational class | DM existing only during Preg. Consider also unrecognized type II DM. | ||
| A1 | Diet controlled, no meds to control bld sugar | ||
| A2 | Requires medication (oral, or injected insulin) for control | ||
| Pregestational class | Onset age (y) | Duration (y) | Complications |
| B | ³20 | <10 | None |
| C | 10–19 | 10–19 | None |
| D | Before 10 yo | >20 | ± benign retinopathy, other vascular complications |
| F | Any | Any | Nephropathy |
| H | Any | Any | Heart |
| R | Any | Any | Proliferative retinopathy |
| T | Any | Any | Renal xplant |
Screening for DM in Pregnancy
- Univ GDM screening Screen early if risk factors. Consider no screening by criteria.
- On 50 g oral gluc challenge test, serum gluc ³140 mg/dL identifies 80% GDM;
³130 mg/dL identifies 90% GDM. Serum gluc ³200 mg/dL ® GDM w/o other testing. Positive screening test ® 3 h fasting gluc challenge (100 g test; diagnostic table, below).
- 3-h OGTT: Consume ³150 g of carbohydrate per day for 3 d, then 100 g oral gluc challenge ® fasting + 1-, 2-, 3-h post challenge bld gluc. 1 abn value = gluc intolerance (a/w fetal macrosomia). Dx of GDM made ³2 abn values.
- New Endo one step Guideline differs from ACOG (J Clin Endo Metab 2013;98:4227) Universal DM testing before 13w gest, repeat if abnormal on different day to
8–14hr Fasting gluc ³126 mg/dL, untimed ³200mg/dL, or HbA1C ³6.5% = overt DM; Fasting 92-125 mg/dL = GDM
24-28w screen if not prev dx, w/ 75g OGTT (after 8hr fast) Fasting gluc >126mg/dL or 2hr >200 mg/dL = overt DM;
Fasting 92–125 mg/dL or 1hr >180 mg/dL or 2hr 153–199 mg/dL = GDM
| Gestational diabetes risk assessment |
| Low risk |
| Age younger than 25 yo |
| Not a member of an ethnic group with increased risk for type 2 DM (Hispanic, African, Native American, South or East Asian, or Pacific Islander ancestry) |
| BMI <25; normal weight at birth |
| No h/o abnormal glucose tolerance |
| No h/o poor obstetric outcomes |
| No 1st degree relatives with DM |
| High risk |
| Severe obesity |
| Strong FHx of type 2 diabetes |
| Previous h/o GDM, impaired glucose metabolism, or glucosuria |
| Patients who meet all low-risk criteria and have no high-risk factors may forgo oral glucose challenge testing if appropriate.
From Metzger BE, Buchanan TA, Coustan DR, et al. Summary and Recommendations of the Fifth International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes Care. 2007;30(2):S251. |
| Criteria for diagnosis of gestational diabetes from oral glucose tolerance testing | ||
| Time since 100-g
glucose load (h) |
Modified O’Sullivan scale |
Carpenter and Coustan scale |
| Fasting | ³105 | ³95 |
| 1 | ³190 | ³180 |
| 2 | ³165 | ³155 |
| 3 | ³145 | ³140 |
| Values are plasma glucose levels in mg/dL.
From O’Sullivan JB, Mahan CM. Criteria for the oral glucose tolerance test in pregnancy. Diabetes. 1964;13:278– 285 and Carpenter MW, Coustan DR. Criteria for screening tests for gestational diabetes. Am J Obstet Gynecol. 1982;144:768–773. |
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Management of DM in Pregnancy
- GDM
Nutrition advice, diet/exercise, & 4´/d bld gluc testing (fasting + 1or 2-h postprandial) If inadeq control ® oral hypoglycemic agents (glyburide), if inadeq w/ max dose ® insulin GDM-A1 no monitoring, no early deliv (routine induction at 41–42 or for OB
indications)
GDM-A2 antenatal testing (NST/BPP from 32–34 w) & deliver by 40 w
| Goals for glycemic control in pregnancy | |
| Goal blood sugar values | |
| Fasting | 60–90 mg/dL |
| Premeal | <100 mg/dL |
| 1 h postprandial | <140 mg/dL |
| 2 h postprandial | <120 mg/dL |
| Bedtime | <120 mg/dL |
| 2–6 AM | 60–90 mg/dL |
| From Metzger BE, et al. Summary and Recommendations of the Fifth International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes Care. 2007;30(2):S251. | |
• Pregestational diabetes
Diet: 1800–2400 kcal daily, w/ 20% prot, 60% carbs, & 20% fat.
The American Diabetes Association recommends insulin for pregnant women w/ type I or II DM. NPH & rapid-acting insulin combination used (see Table with insulin types, above).Type I DM usually insulin 50–100%. Type II DM often
>200% in Preg. Consider baseline HELLP labs, thyroid testing (40% type I DM – thyroid d/o) & 24-h urine prot early Preg.
Eye exam in 1st trimester, & baseline ECG (age >30 y or hypertensive).
Pregestational DM obtain early sonogram, confirm viability, offer mat serum AFP for NT defects, US for anatomy & fetal echocardiography.
1–2´/w fetal NST/AFI from 32–34 w or earlier. Serial fetal growth scans every 4–6 w to eval for IUGR or macrosomia. Deliv not later than 39–40 w, depending on gluc control in Preg.
Figure 17.2 Calculation and dose distribution for initial insulin management in pregnancy
(From Gabbe SG. Management of diabetes mellitus complicating pregnancy. Obstet Gynecol 2003;102(4):857)
Labor and Delivery for Diabetics
- Consider cesarean deliv for EFW >4500 g for pts w/ diabetes (>5000 g for nondiabetic)
- Insulin mgmt during labor: Usual intermediate insulin at Morning dose insulin withheld. W/ active labor or gluc <70 mg/dL start D5NS IVF. Check bld gluc hourly in labor. Usually pregestational DM ® IV insulin drip & titrate. Tight gluc control to avoid neonat hypoglycemia.
- Fetal lung maturity may be delayed in DM, even with reassuring FLM
Postpartum Management
- Usually insulin-dependent pregestational DM ® resume prepregnancy regimen, or ½
of end Preg dose. GDM can stop rx, unless suspected DM 2. GDM resolves w/ deliv.
- Postpartum 75 g gluc tol test to identify nongestational DM for all GDM
| Postpartum glucose tolerance test | |||
|
No DM |
Impaired glucose
tolerance |
Overt DM |
|
| 8 h fasting | <100 | 100–125 | ³126 |
| 2 h after 75 g glucose load | <140 | 140–199 | ³200 |
| Values are plasma glucose levels in mg/dL.
From Metzger BE, et al. Summary and Recommendations of the Fifth International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes Care. 2007;30(2):S251 and American Diabetes Association Standards of Medical Care in Diabetes—2010. Diabetes Care. 2010;33:S11–S61. |
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Gestational Diabetes (GDM)
Definitions, Epidemiology, and Pathophysiology
- GDM is carbohydrate intolerance w/ onset or 1st recognition during Preg
- Classification: A1GDM is diet controlled;A2GDM requires pharmacologic intervention
- GDM in ~5–10% of 20–50% will ® nongestational DM in 10 y; 30–50%
® recurrent GDM.
- human placental lactogen/cortisol/progesterone/estrogen ® ¯ periph insulin sens ®
impaired gluc resp ® hyperglycemia. Screening per above, under Diabetes in Pregnancy
Treatment and Medications
- See mgmt in Diabetes in Pregnancy,
- Oral hypoglycemics considered if dietary mgmt Glyburide equiv to insulin for gluc control (starting dose: 1.25–2.5 mg twice daily ® 2.5 mg as needed; max 10 mg BID). Insulin needs markedly btw 28 & 32 w gest (Obstet Gynecol 2003;102(4):857). See starting insulin schematic, above. Consider lower dose for insulin naive pt.