Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

pregnant

1st line – diet, exercise, + glucose monitoring

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ACUTE
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pregnant
1st line – 

diet, exercise, + glucose monitoring

Lifestyle interventions, including education, healthy eating, physical activity, and self-monitoring of blood sugar levels, are first-line treatment for women with GDM.[1][72]​ Most women who have GDM detected by screening are adequately treated with lifestyle measures alone. All women should be referred to a registered dietitian, if available.[1]​​[23]​ Nutrition counseling should endorse a balance of macronutrients including nutrient-dense fruits, vegetables, legumes, whole grains, and healthy fats with omega-3 fatty acids that include nuts and seeds and fish in the eating pattern.[1]​ The nutrition plan should emphasize monounsaturated and polyunsaturated fats while limiting saturated fats and avoiding trans fats. Processed foods, fatty red meat, and sweetened foods and beverages should be limited.[1] Usual prenatal care including folate supplementation should be continued.

There is no definitive research that identifies a specific optimal calorie intake for people with GDM or suggests that their calorie needs are different from those of pregnant individuals without GDM.[1] The American Diabetes Association (ADA) advises that the food plan should provide adequate calorie intake to promote fetal/neonatal and maternal health, achieve glycemic goals, and promote appropriate weight gain, according to the 2009 National Academy of Medicine recommendations for weight gain during pregnancy.[1][33]

As is true for all nutrition therapy in people with diabetes, the amount and type of carbohydrate will impact glucose levels. Promoting higher-quality, nutrient-dense carbohydrates results in controlled fasting/postprandial glucose, lower free fatty acids, improved insulin action, and vascular benefits and may reduce excess infant adiposity.[1] Complex carbohydrates are recommended over simple carbohydrates because they are digested more slowly, are less likely to produce significant postprandial hyperglycemia, and potentially reduce insulin resistance.[51] A meta-analysis of dietary interventions concluded that a low glycemic index (GI) diet was associated with a less frequent need for insulin and lower infant birth weights than calorie-restricted diets, low carbohydrate diets, or other diets.​[79]​ The ADA warns that individuals who substitute fat for carbohydrates may unintentionally enhance lipolysis, promote elevated free fatty acids, and worsen maternal insulin resistance.[1] Fasting urine ketone testing may be useful to identify those who are severely restricting carbohydrates to manage blood glucose.[1]

Moderate-intensity exercise (e.g., brisk walking, easy jogging, or swimming) during pregnancy is recommended and has been associated with lowering of maternal glucose levels in some but not all studies.[51][80]​​ American College of Obstetricians and Gynecologists (ACOG) guidelines comment that there are few published exercise trials in women with GDM, and most of these trials have small sample sizes; however, they do appear to show improvement in glucose levels.[51] They recommend that exercise plans should mirror diabetes care in general, and women with GDM should aim for 30 minutes of moderate-intensity aerobic exercise at least 5 days a week or a minimum of 150 minutes per week. Simple exercise such as walking for 10-15 minutes after each meal can lead to improved glycemic control and is commonly recommended.[51]

Self-monitoring of blood glucose is initiated to assess fasting and postprandial glycemia and guide therapy.[1]​ ​ACOG guidelines note that there is insufficient evidence to define the optimal frequency of blood glucose testing in women with GDM; however, based on the available data, the general recommendation is for glucose monitoring four times a day, once after fasting and again after each meal. In patients whose glucose levels are well controlled by diet, the frequency of glucose monitoring may be modified depending on gestational age, overall concerns for concordance, and likely need for future adjustments in care. However, it is unusual to recommend obtaining fewer than two measurements per day.[51]​ ​The ADA notes that continuous glucose monitoring can help to achieve HbA1c targets in pregnancy when used in addition to pre- and postprandial blood glucose monitoring.[1]

Target blood glucose levels in GDM are preprandial <95 mg/dL (<5.3 mmol/L), plus either 1-hour postprandial <140 mg/dL (<7.8 mmol/L) or 2-hour postprandial <120 mg/dL (<6.7 mmol/L).[1][42]​​​[51]​​​[63]

Plus – insulin therapy

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ACUTE
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pregnant
|
uncontrolled with dietary therapy, or marked initial hyperglycemia
Plus – 

insulin therapy

Treatment recommended for ALL patients in selected patient group

Approximately 1 in 4 individuals will require pharmacotherapy in addition in order to achieve glycemic targets.[69] Pharmacologic treatment is recommended when target glucose levels cannot be consistently achieved through nutrition therapy and exercise.[51]

Insulin has historically been considered the standard therapy for GDM management in cases refractory to nutrition therapy and exercise and this has continued to be reinforced by the American Diabetes Association (ADA).[51] Insulin can achieve tight metabolic control and has traditionally been added to nutrition therapy if fasting blood glucose levels are consistently greater than or equal to 95 mg/dL, if 1-hour levels consistently are greater than or equal to 140 mg/dL, or if 2-hour levels consistently are greater than or equal to 120 mg/dL.[51] These thresholds have largely been extrapolated from recommendations for managing pregnancy in women with preexisting diabetes.[51] A systematic review found no conclusive evidence for a specific threshold value at which medical therapy should be started.[82] A study of women with GDM treated with dietary therapy for 4 weeks before initiating insulin found that most women who achieved good control with diet did so within 2 weeks and had baseline fasting plasma glucose levels of <95 mg/dL.[83] Accordingly, the authors recommended that patients with a fasting plasma glucose <95 mg/dL attempt dietary therapy for at least 2 weeks before starting insulin, whereas insulin should be started at diagnosis or within a week of failed dietary therapy in patients with fasting glucose levels >95 mg/dL.[83] Such severe elevations imply the need for aggressive therapy with prompt initiation of insulin. 

Immediate initiation of insulin is appropriate for women with more severe hyperglycemia, such as those with symptomatic hyperglycemia, fasting plasma glucose >125 mg/dL, or random plasma glucose >200 mg/dL.

Insulin management in pregnancy is often complex and commonly requires frequent dose titration; the ADA recommends referral to a specialized center offering team-based care for women prescribed insulin in pregnancy, if this is available.[1] B​oth multiple daily insulin injections and continuous subcutaneous insulin infusion are reasonable delivery strategies, and neither has been shown to be superior to the other during pregnancy.[51]

Target blood glucose levels in GDM are preprandial <95 mg/dL (<5.3 mmol/L), plus either 1-hour postprandial <140 mg/dL (<7.8 mmol/L) or 2-hour postprandial <120 mg/dL (<6.7 mmol/L).[1]​​[42][51]​​​[63]​​​

Insulin needs are highly variable. Requirements increase through pregnancy and average 0.8 units/kg/day in the first trimester, 1 unit/kg/day in the second trimester, and 1.2 units/kg/day in the third trimester, before dropping dramatically after delivery.[1][84] The daily dosage should be divided with a regimen of multiple injections using long-acting or intermediate-acting insulin in combination with short-acting insulin. However, if there are only isolated abnormal values at a specific time of day, focusing the insulin regimen to correct the specific hyperglycemia is preferred.[51] 

Insulin therapy requires highly individualized titration. For isolated fasting hyperglycemia, a useful approach is to start intermediate-acting insulin (e.g., insulin NPH [Neutral Protamine Hagedorn]) or long-acting insulin (e.g., insulin glargine) at bedtime and adjust dose to achieve fasting blood glucose <95 mg/dL.[51][85]​​ To address postprandial hyperglycemia, one approach is to use intermediate-acting or long-acting insulin once or twice daily, with short-acting prandial insulin (e.g., insulin lispro, insulin aspart) titrated to meet glycemic targets.[42][85]

Correction doses may be used for individual modification of insulin regimens.

When used at therapeutic doses, insulin does not cross the placenta and is generally considered safe. For long-acting and intermediate-acting insulin, NPH insulin has been the mainstay, but more recently long-acting insulin glargine has been used.[51] Insulin detemir was frequently used instead of insulin glargine, especially in Europe, but production of insulin detemir has been discontinued. Although there is more limited experience with the long-acting analogs, there is no evidence of adverse maternal or fetal outcomes with these agents.[51]​​[85][86][87][88]​ For short-acting insulin, insulin lispro and insulin aspart should be used preferentially over regular human insulin because both have a more rapid onset of action, enabling the patient to administer their insulin right at the time of a meal rather than 10-15 minutes before an anticipated meal. This provides better glycemic control and helps avoid hypoglycemic episodes from errors in timing.[51]

Primary options

insulin NPH

or

insulin glargine

-- AND --

insulin lispro

or

insulin aspart

Consider – initiate antepartum fetal assessment

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ACUTE
|
pregnant
|
32 weeks’ gestation
Consider – 

initiate antepartum fetal assessment

Treatment recommended for SOME patients in selected patient group

Guidelines from the American College of Obstetricians and Gynecologists (ACOG) advise that fetal surveillance in women with poorly controlled or medication-requiring GDM without other morbidities is usually initiated at 32 weeks of gestation.[51] If other factors associated with increased risk of adverse pregnancy outcome are present, it may be reasonable to start surveillance earlier in pregnancy.[51] There is no consensus regarding antepartum fetal testing among women with well-controlled GDM who are not medically treated; studies have not specifically demonstrated an increase in stillbirth with GDM well-controlled with medication before 40 weeks of gestation.[51] If antepartum testing is to be used in such patients, it is generally started later than in women who require antihyperglycemic medication.[51] The specific antepartum test and frequency of testing may be chosen according to local practice; however, because polyhydramnios can result from fetal hyperglycemia, it is common for clinicians to use testing that incorporates serial measures of amniotic fluid.[51] For women with poor GDM control and those requiring insulin therapy, more intensive fetal monitoring with nonstress tests, or biophysical profile assessments once or twice weekly is indicated to reduce the risk for stillbirth.[23][92]​​

Ultrasound-assessed abdominal circumference and estimated fetal weight may be indirect indicators of glycemic control in patients with GDM; however, fetal growth is driven by multiple factors.[78] As increasing fetal size is associated with increased risk of shoulder dystocia and birth trauma, assessment of fetal size, either clinically or with ultrasound, may also be useful in planning delivery route. It should be noted that ultrasound overestimates the prevalence of large-for-gestational-age fetal weight in women with GDM.[90] Although it is reasonable to offer cesarean delivery to reduce the risk for shoulder dystocia if the estimated fetal weight is >4500 g, the estimation of fetal weight regardless of modality is imprecise, and therefore counseling should be individualized; fetal macrosomia is not itself an indication for delivery.[91] It has been estimated that up to 588 cesarean deliveries would be needed to prevent a single case of permanent brachial plexus palsy for an estimated fetal weight of 4500 g, and up to 962 cesarean deliveries would be needed for an estimated fetal weight of 4000 g.[51]

labor

1st line – intrapartum glycemic control

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ACUTE
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labor
1st line – 

intrapartum glycemic control

Intrapartum glycemic monitoring is widely recommended in women with GDM requiring insulin.[94] There are no large randomized controlled trials of intrapartum glycemic control to lessen the risk of neonatal hypoglycemia; however, based on limited evidence, avoiding maternal hyperglycemia in women with GDM during labor is recommended, and may require intravenous insulin to achieve.[95]

The Joint British Diabetes Societies (JBDS) for Inpatient Care Group recommend that all women with diabetes of any type should have hourly blood glucose (capillary, flash, or continuous glucose monitoring [CGM]) monitoring in established labor or from the morning of elective cesarean section.[66]​ In addition, it adds that if general anesthesia is used, monitoring should be every 30 minutes until the woman is fully conscious.[66]​​

In the UK, it is recommended that glucose levels are maintained during labor in either the target range advocated in the National Institute of Health and Care Excellence guidelines (4.0 to 7.0 mmol/L [72 to 126 mg/dL]) or in the more liberal range of 5.0 to 8.0 mmol/L (90 to 144 mg/dL) due to lack of randomized controlled trial evidence for either target.[19][66]​​ Some women with GDM may require variable rate intravenous insulin infusion to achieve target glucose levels.[66]​​

Many women with GDM require no insulin during labor.

Immediately after placental delivery, a large reduction in insulin requirement occurs, and this must be anticipated to avoid hypoglycemia. Initial postpartum insulin needs are generally as low as, or lower than, prepregnancy requirements.

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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