What are the target time in range glucose goals for Gestational Diabetes Mellitus (GDM)?

From the Guidelines

For gestational diabetes, the target time in range glucose goal is typically below 95 mg/dL (5.3 mmol/L) for fasting, below 140 mg/dL (7.8 mmol/L) for 1-hour postprandial, and below 120 mg/dL (6.7 mmol/L) for 2-hour postprandial levels, as recommended by the most recent guidelines 1. These targets help minimize complications like macrosomia, neonatal hypoglycemia, and cesarean delivery. To achieve these goals, pregnant women should monitor blood glucose 4-7 times daily: fasting and either 1 or 2 hours after each meal. Initial management includes dietary modifications (distributing carbohydrates throughout the day, emphasizing complex carbohydrates, and limiting simple sugars) and moderate exercise (30 minutes daily if approved by healthcare provider). If glucose targets aren't met with lifestyle changes after 1-2 weeks, medication therapy may be necessary, with insulin being the preferred option during pregnancy, as supported by recent studies 1. Key points to consider in managing gestational diabetes include:

• Fasting blood glucose should be below 95 mg/dL (5.3 mmol/L) 1
• 1-hour postprandial levels should stay below 140 mg/dL (7.8 mmol/L) 1
• 2-hour postprandial levels should be below 120 mg/dL (6.7 mmol/L) 1
• A1C goals should be individualized, but ideally below 6% (42 mmol/mol) if achievable without significant hypoglycemia 1
• Continuous glucose monitoring can be beneficial for achieving glycemic goals in pregnancy, especially for type 1 diabetes 1. The importance of these strict glucose targets lies in their impact on fetal growth and development, as maternal hyperglycemia directly affects the fetus through increased glucose transfer across the placenta, stimulating fetal insulin production and potentially leading to excessive fetal growth 1.

From the Research

Target "Time in Range" Glucose Goals for Gestational Diabetes

• The target "time in range" glucose goals for gestational diabetes is a topic of interest in recent studies 2.
• A study published in 2024 found that a time in range (TIR) of >70% is associated with better maternal and neonatal outcomes in women with gestational diabetes mellitus (GDM) or type 2 diabetes mellitus (T2DM) 2.
• The same study found that individuals with TIR ≤70% had a higher likelihood of adverse neonatal and maternal outcomes, including large for gestational age, NICU admission, need for intravenous glucose, respiratory support, or neonatal death 2.
• Another study published in 2013 found that metformin can provide adequate glycemic control with lower mean glucose levels throughout the day, less weight gain, and a lower frequency of neonatal hypoglycemia in women with GDM 3.
• However, the study also found that 26.08% of women in the metformin group required supplemental insulin for glycemic control, and that early gestational age at diagnosis and mean pretreatment glucose level were predictors of the need for insulin 3.

Glucose Monitoring and Management

• Continuous glucose monitoring (CGM) has become available for women with GDM or T2DM during pregnancy, and can be used to monitor time in range and adjust treatment accordingly 2.
• A study published in 2021 found that lifestyle modifications, including nutritional therapy and exercise, are recommended for the management of GDM, and that pharmacological treatment, including insulin and metformin, may be necessary if conservative strategies fail to provide expected glucose levels 4.
• Another study published in 2019 found that metformin can be an effective substitute for insulin in the treatment of GDM, but that there are still some undesirable risk factors associated with both treatments 5.

Clinical Implications

• The findings of these studies suggest that a time in range of >70% is a desirable goal for women with GDM or T2DM, and that CGM can be a useful tool for monitoring and managing glucose levels during pregnancy 2.
• The studies also highlight the importance of individualized treatment approaches, taking into account factors such as gestational age at diagnosis, mean pretreatment glucose level, and the need for supplemental insulin therapy 3.