Melatonin for Glycemic Control in Gestational Diabetes Mellitus (MELODY)

Efficacy of Melatonin in Addition to Standard Care in Glycemic Control of Patients With Gestational Diabetes Mellitus: a Randomized, Double-blind, Placebo-controlled Trial

The goal of this randomized, double-blind, placebo-controlled clinical trial is to evaluate whether melatonin supplementation improves glycemic control in pregnant women diagnosed with gestational diabetes mellitus (GDM).

The main question it aims to answer is:

Does melatonin supplementation help with glycemic control, especially in lowering fasting plasma glucose level?

Researchers will compare melatonin to a placebo (a look-alike substance that contains no melatonin) to see if melatonin works to improve glycemic control.

Participants will:

1. Take melatonin or a placebo every day after randomization until delivery
2. Visit the antenatal clinic once every 1 to 2 weeks for follow-ups

Study Overview

• Status: Not yet recruiting
• Conditions: Gestational Diabetes
• Intervention / Treatment: Drug: Melatonin; Other: Placebo

• Study Type: Interventional
• Enrollment (Estimated): 150
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Yanting Wu, PhD; Phone Number: 8621-17321218018; Email: yanting_wu@163.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Women aged 18 to 45 years
• Singleton pregnancy
• A diagnosis of GDM from a 75-g OGTT during 24 to 28 gestational weeks, according to the IADPSG criteria, with at least fasting plasma glucose (FPG) ≥ 5.1 mmol/L
• Intending to receive obstetric care and deliver in the study center
• Willing and able to provide written informed consent and follow the study procedure

Exclusion Criteria:

• Use of melatonin 1 month before pregnancy or/and during pregnancy
• Night shift work or exposed to jetlag on a regular basis during pregnancy
• Contraindications to melatonin use, including hypersensitive or allergic to melatonin
• Use of antidepressive or antipsychotic medications which can interfere with melatonin metabolism and/or elimination, such as fluvoxamine, 5- or 8-methoxypsoralen, cimetidine, quinolones, and other CYP1A2 inhibitors; carbamazepine, rifampicin, and other CYP1A2 inducers; and zaleplon, zolpidem, zopiclone, and other non-benzodiazepine hypnotics
• Pre-pregnancy diabetes, including patients diagnosed with diabetes before conception, fasting plasma glucose ≥ 7.0 mmol/L or HbA1c ≥ 6.5% in the first trimester, typical hyperglycemic symptoms or hyperglycemic crisis with random blood glucose ≥ 11.1 mmol/L
• Other major diseases before gestation, e.g. hypertensive disorders, rheumatology or malignant diseases, infected with hepatitis B or hepatitis C, chronic diseases leading to impaired heart, liver, or renal function
• Major fetal anomalies

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Melatonin; Melatonin tablets will be administered orally 0.5 to 1 hour before sleep and at least 2 hours after the last meal.; Participants will take 5 mg melatonin every night during the first week of intervention after randomization, followed by 10 mg melatonin every night from the second week until delivery.	Drug: Melatonin; Melatonin tablets will be administered orally 0.5 to 1 hour before sleep and at least 2 hours after the last meal.; Participants will take 5 mg melatonin every night during the first week of intervention after randomization, followed by 10 mg melatonin every night from the second week until delivery.
Placebo Comparator: Placebo; Identical placebo tablets in terms of packaging, appearance, smell and taste will be administered orally 0.5 to 1 hour before sleep and at least 2 hours after the last meal.; Participants will take identical placebo tablets after randomization until delivery.	Other: Placebo; Identical placebo tablets in terms of packaging, appearance, smell and taste will be administered orally 0.5 to 1 hour before sleep and at least 2 hours after the last meal.; Participants will take identical placebo tablets after randomization until delivery.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in fasting plasma glucose (FPG) from baseline to 36 to 38 gestational weeks	The primary outcome is defined as the change in FPG levels from baseline, measured at the time of OGTT performed between 24 and 28 gestational weeks, to follow-up assessment at 36 to 38 gestational weeks. For participants who deliver before 36 gestational weeks, the last available FPG measurement obtained will be used.	Baseline (24 to 28 gestational weeks), and 36 to 38 gestational weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in glycated hemoglobin (HbA1c) from baseline to 36 to 38 gestational weeks	This outcome is defined as change in HbA1c levels from baseline, measured at the time of OGTT performed between 24 and 28 gestational weeks, to follow-up assessment at 36 to 38 gestational weeks.	Baseline and 36 to 38 gestational weeks
Initiation of insulin therapy	This outcome is defined as the proportion of participants requiring initiation of insulin therapy.	From baseline until delivery
Change in mean glucose levels assessed by continuous glucose monitoring (CGM)	This outcome is defined as the change in mean glucose levels measured by CGM at baseline and before delivery.	Baseline and 36 to 38 gestational weeks
Gestational weight gain in late pregnancy	This outcome is defined as total gestational weight gain and the rate of weight gain from baseline to the last assessment prior to delivery.	From baseline until delivery
Incidence of intervention-related adverse events	This outcome is defined as the proportion of participants reporting adverse events potentially related to study intervention, including but not limited to dizziness, hypersomnia, nausea, vomiting and hypoglycemia. Adverse events will be collected from participants' medication diaries and systematically assessed through participant self-report at each antenatal clinic visit.	From initiation of the intervention until 6 weeks postpartum
Impact of melatonin on fetal growth	The antenatal use of melatonin on estimated fetal growth (grams) will be assessed using ultrasound biometry parameters performed every two to four weeks following trial recruitment until birth.	From baseline until delivery
Percentage of time in range, time above range, and time below range measured by CGM	This outcome is defined as percentages of time in range, time above range, and time below range measured by CGM at baseline and before delivery.	Baseline and 36 to 38 gestational weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pregnancy complications	This outcome is defined as a series of pregnancy complications including but not limited to gestational hypertensive disorders and intrahepatic cholestasis of pregnancy.	From baseline until the end of follow-up at 6 weeks postpartum
Perinatal outcomes	This outcome is defined as a series of perinatal outcomes including but not limited to the percentages of macrosomia, large for gestational age, small for gestational age, neonatal hypoglycemia, birth trauma, cesarean section, postpartum hemorrhage, placenta abruption, and spontaneous premature rupture of membranes.	From baseline until the end of follow-up at 6 weeks postpartum

Collaborators and Investigators

• Sponsor: Obstetrics & Gynecology Hospital of Fudan University
• Collaborators: West China Second University Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): February 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): August 1, 2027

Study Registration Dates

• First Submitted: January 5, 2026
• First Submitted That Met QC Criteria: January 17, 2026
• First Posted (Actual): January 27, 2026

Study Record Updates

• Last Update Posted (Actual): January 27, 2026
• Last Update Submitted That Met QC Criteria: January 17, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Melatonin; Gestational diabetes; Fasting plasma glucose
• Additional Relevant MeSH Terms: Urogenital Diseases; Endocrine System Diseases; Female Urogenital Diseases and Pregnancy Complications; Metabolic Diseases; Pregnancy Complications; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Diabetes, Gestational; Hormones; Hormones, Hormone Substitutes, and Hormone Antagonists; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Indoles; Tryptamines; Melatonin
• Other Study ID Numbers: 2025-260

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No