Gestational Diabetes and Pharmacotherapy (GAP)

Study Overview
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Brief Summary
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The goal of this study is to compare two different thresholds for initiation of medical treatment for GDM. Pregnant women diagnosed with GDM will be randomized to either start pharmacotherapy when they have reached at least 20% or at least 40% of capillary blood glucose (CBG) values above the target goal. The investigators hypothesize that a lower threshold of 20% elevated CBG levels, compared to 40%, will lead to lower rates of obstetric and medical complications.

Detailed Description
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Gestational diabetes mellitus (GDM) affects 5-8% of pregnant women, many of whom will require treatment beyond diet and exercise. Despite this high prevalence, there is no consensus regarding the glycemic threshold for conversion from diet to medical treatment for GDM. No randomized studies have been performed on how to define failure with diet and exercise and currently, the need to start insulin or oral hypoglycemic agents is at the provider's discretion. It is important to establish criterion of pharmacotherapy initiation for GDM in pregnancy as GDM under-treatment leads to increased rates of adverse obstetric outcomes associated with poor glycemic control including macrosomia, pre-eclampsia, cesarean delivery, shoulder dystocia, birth trauma, neonatal hypoglycemia and hyperbilirubinemia, childhood obesity and metabolic syndrome in the offspring. In contrast, overtreatment for women comes at increased cost due to overutilization of resources, increased expense, and adverse effects of the medications themselves. The goal of this study is to compare two different thresholds for initiation of medical treatment for GDM. Pregnant women diagnosed with GDM (N=416) will be randomized to either start pharmacotherapy when they have reached at least 20% or at least 40% of capillary blood glucose (CBG) values above the target goal. The investigators hypothesize that a lower threshold of 20% elevated CBG levels, compared to 40%, will lead to lower rates of obstetric and medical complications. Aim 1: Determine the effect of earlier insulin initiation (20% threshold) for GDM management on adverse neonatal and maternal outcomes associated with GDM. Hypothesis 1.1: The composite adverse neonatal outcome associated with GDM (LGA, macrosomia, birth trauma, preterm birth, neonatal hypoglycemia, and hyperbilirubinemia) will be lower in earlier insulin initiation compared with the active control group. Hypothesis 1.2: Preeclampsia and cesarean birth frequencies will be lower in earlier insulin initiation compared with the active control group. Hypothesis 1.3: The composite neonatal and maternal outcomes will not differ between racial and ethnic groups within each study group. Aim 2:Assess the safety of earlier insulin initiation in pregnant patients and their neonates. Hypothesis 2.1: The SGA rate will be higher in earlier insulin initiation compared with the active control group; however, in both groups it will be lower than the national rate of 10%. Hypothesis 2.2: Maternal hypoglycemia and perinatal death will not differ between groups. Aim 3:Determine the effect of earlier insulin initiation on patient-reported outcomes using standardized measures and qualitative interviews. Hypothesis 3: Anxiety, depression, perceived stress and diabetes self-efficacy will be better in patients randomized to earlier insulin initiation compared with the active control group.

Official Title
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Gestational Diabetes and Pharmacotherapy (GAP) - A Randomized Controlled Trial Investigating Timing of Pharmacotherapy Initiation for Patients With Gestational Diabetes

Conditions
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Gestational Diabetes

Intervention / Treatment
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* Drug: Insulin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Viable singleton pregnancy Age >= 18 years old Diagnosed with gestational diabetes mellitus Able to communicate in English Exclusion Criteria: Pre-gestational diabetes Significantly abnormal GDM testing, suggestive of the presence of pre-gestational diabetes, either with fasting values >=126 mg/dL or 2-hour post-prandial levels >=200 mg/dL Patients who check blood sugars on average less than 2 times per day after appropriate counseling Already started pharmacotherapy prior to referral to the study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: This will be a randomized, controlled trial of 284 women with a diagnosis of GDM. Women will be consented and randomized at the time of their diagnosis. All women with GDM will receive counseling regarding diet and exercise and instructions on self-monitoring blood glucose values. The investigators will apply cutoffs of 95 mg/dL for fasting and 120 mg/dL for 2-hour post-prandial levels. Once randomized, the first treatment arm will be assigned to a limit of 20% abnormal values before we start treatment and to titrate up dosages as needed, while using the 20% threshold of abnormal CBG values at each subsequent review of glucose log. To specify, if more than 20% of values for the week are elevated, treatment would be initiated. Once treatment is initiated, the dosage of medication will be adjusted with cutoff of 20% of abnormal values per week. The second treatment arm will utilize the same protocol, however, the limit to start medications or adjust dosages will be 40% abnormal values.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 20% cutoff group<br>Treatment intervention will be initiated with insulin if 20% cutoff of abnormal values is reached. Medication dosages will depend on the physician's discretion. | Drug: Insulin<br>* Insulin may be administered base on glucose log values. The dosing of the insulin will be determined by the provider using typical management of gestational diabetes.<br>|
| Active Comparator: 40% cutoff group<br>Treatment intervention will be initiated with insulin if 40% cutoff of abnormal values is reached. Medication dosages will depend on the physician's discretion. | Drug: Insulin<br>* Insulin may be administered base on glucose log values. The dosing of the insulin will be determined by the provider using typical management of gestational diabetes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Composite Neonatal Outcome | Our primary outcome will be a composite adverse neonatal outcome associated with gestational diabetes: large-for-gestational age macrosomia birth trauma preterm birth neonatal hypoglycemia hyperbilirubinemia | The data will be collected up to 6 weeks of life | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cesarean Delivery Rate | Our secondary outcome will be to compare the rates of cesarean delivery between two thresholds for medical treatment initiation for GDM. | The data will be collected up to 6 weeks postpartum | 
| Preeclampsia |  | The data will be collected up to 6 weeks postpartum |