Effect of Using Bitter Melon, Blueberries and Cranberries on HbA1c and Diabetes Symptom Levels

November 18, 2025 updated by: Hatice Demirağ, Ph.D

Effect of Use of Bitter Melon, Blueberry and Cranberry as Complementary Therapy on HbA1c and Diabetes Symptom Level in Individuals With Type 2 Diabetes Mellitus: Single-blind Randomized Controlled Study

This double-blind, randomized controlled trial investigated the effect of bitter melon, blueberry, and cranberry powder extract use on glycemic control and diabetes symptom levels in individuals with T2DM.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The increasing prevalence of Type 2 Diabetes Mellitus (T2DM) worldwide and the search for additional support to current treatments have increased interest in researching natural components such as bitter melon, blueberry, and cranberry, known for their antioxidant and hypoglycemic potential, as complementary therapies. This double-blind, randomized controlled trial investigated the effect of bitter melon, blueberry, and cranberry powder extract use on glycemic control and diabetes symptom levels in individuals with T2DM.

The study, conducted with four groups (bitter melon, blueberry, cranberry, and control), included 120 individuals diagnosed with T2DM. Individuals in the experimental group used 10g of powdered extract daily for 12 weeks, while those in the control group used nothing. The 'Patient Information Form' and 'Diabetes Symptoms Checklist Scale' were administered before the start of the study (pre-test/week 0) and at the end (post-test/week 12), and the venous blood value of the Hemoglobin A1c test (HbA1c) was measured.

In the experimental groups (bitter melon, blueberry, cranberry), after 12 weeks of treatment, statistically significant decreases were observed in HbA1c, the total score and all Subdimensions scores of the 'Diabetes Symptoms Checklist Scale', weight, and BMI compared to the control group; while in the control group, there was a significant increase in all parameters except HbA1c (p<0.05). Although there was no difference between the experimental (bitter melon, blueberry, cranberry) groups in the intergroup measurements, HbA1c, the total mean scores of the Diabetes Symptom Checklist Scale, weight, and BMI were found to be significantly lower than in the control group (p<0.05).

Bitter melon, blueberry, and cranberry powder extracts were found to be equally effective in reducing HbA1c, diabetes symptoms, weight, and BMI in T2DM patients. The lack of difference in efficacy between the three extracts in terms of glycemic and symptom levels suggests that these three natural products can be considered equivalent therapeutic options in the complementary treatment of T2DM.

Study Type

Interventional

Enrollment (Actual)

120

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Being 18 years of age or older,
  • Volunteering to participate in the study,
  • Being conscious and able to communicate,
  • Having been diagnosed with T2DM at least 3 months prior and currently using oral antidiabetic medication,
  • Be using one of the following powder extracts-bitter melon, blueberry, or cranberry-for the first time as a complementary treatment upon a physician's recommendation and be on the first day of use,
  • Not taking any other medications that affect blood sugar,
  • No allergy to bitter melon, blueberry, or cranberry,
  • Not engaging in exercise,
  • Taking 10g of bitter melon, blueberry, or cranberry powder extract daily.

Exclusion Criteria:

  • Not meeting the inclusion criteria, having a known psychological disorder,
  • Having previously received complementary therapy for DM, or having hearing loss.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Supportive Care
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Bitter melon Group
Before starting the study (pre-test/week 0), all group participants first completed the "Patient Information Form" and the "Diabetes Symptom Checklist Scale," and their HbA1c venous blood values were measured. At the end of the study (post-test/12th week), the "Diabetes Symptom Checklist Scale" was administered again to individuals in the three groups, and their HbA1c venous blood values were measured. In addition, telephone follow-up was conducted to determine whether the individuals had used the powdered extracts completely for 12 weeks.
Other: Bitter Melon Group
Patients who voluntarily used bitter melon powder extract continued to consume 1 teaspoon (10 g total) of powdered extract mixed with yogurt or water twice a day (morning and evening) for 12 weeks.
Experimental: Blueberry Group
Before starting the study (pre-test/week 0), all group participants first completed the "Patient Information Form" and the "Diabetes Symptom Checklist Scale," and their HbA1c venous blood values were measured. At the end of the study (post-test/12th week), the "Diabetes Symptom Checklist Scale" was administered again to individuals in the three groups, and their HbA1c venous blood values were measured. In addition, telephone follow-up was conducted to determine whether the individuals had used the powdered extracts completely for 12 weeks.
Other: Blueberry Group
Patients who voluntarily used bitter blueberry powder extract continued to consume 1 teaspoon (10 g total) of powdered extract mixed with yogurt or water twice a day (morning and evening) for 12 weeks.
Experimental: Cranberry Group
Before starting the study (pre-test/week 0), all group participants first completed the "Patient Information Form" and the "Diabetes Symptom Checklist Scale," and their HbA1c venous blood values were measured. At the end of the study (post-test/12th week), the "Diabetes Symptom Checklist Scale" was administered again to individuals in the three groups, and their HbA1c venous blood values were measured. In addition, telephone follow-up was conducted to determine whether the individuals had used the powdered extracts completely for 12 weeks.
Other: Cranberry Group
Patients who voluntarily used cranberry powder extract continued to consume 1 teaspoon (10 g total) of powdered extract mixed with yogurt or water twice a day (morning and evening) for 12 weeks.
No Intervention: Control Group
Before starting the study (pre-test/week 0), all group participants first completed the "Patient Information Form" and the "Diabetes Symptom Checklist Scale," and their HbA1c venous blood values were measured. At the end of the study (post-test/12th week), the "Diabetes Symptom Checklist Scale" was administered again to individuals in the three groups, and their HbA1c venous blood values were measured.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
HbA1c
Time Frame: 12 week

Unlike instant blood glucose values, HbA1c reliably reflects an individual's average blood sugar level over the past two to three months by measuring the amount of glucose bound to hemoglobin during the average lifespan of erythrocytes (approximately 120 days).

Before starting the study (pre-test/week 0) HbA1c venous blood values were measured. Patients who voluntarily used bitter melon, blueberry, or cranberry continued to consume 1 teaspoon (10 g total) of powdered extract mixed with yogurt or water twice a day (morning and evening) for 12 weeks. At the end of the study (post-test/12th week), the was administered again to individuals HbA1c venous blood values were measured.
12 week
Diabetes Symptom Checklist Scale
Time Frame: 12 week

The scale consists of a total of 34 items. These categories are: neurology (3, 11, 15, 21, 25, 34), psychology (1, 2, 4, 6, 17, 20), cardiology (5, 8, 9, 13, 24, 26, 29, 30), ophthalmology (10, 14, 22, 28), psychology/cognition (7, 19, 27, 31, 33), and hyperglycemia (12, 16, 23, 32) Subdimensionss. Responses on the scale are numbered from 0 to 5, with "0" meaning "none" and "5" meaning "extremely."

Before starting the study (pre-test/week 0), all group participants first completed "Diabetes Symptom Checklist Scale" were measured. Patients who voluntarily used bitter melon, blueberry, or cranberry continued to consume 1 teaspoon (10 g total) of powdered extract mixed with yogurt or water twice a day (morning and evening) for 12 weeks. At the end of the study (post-test/12th week), the "Diabetes Symptom Checklist Scale" was administered again to individuals were measured.
12 week

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hatice Demirağ, Ph.D

Collaborators

Karadeniz Technical University

Investigators

  • Principal Investigator: Hatice Demirağ, Study Principal Investigator Gümüşhane Universıty

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 6, 2024

Primary Completion (Actual)

February 15, 2024

Study Completion (Actual)

May 15, 2024

Study Registration Dates

First Submitted

November 14, 2025

First Submitted That Met QC Criteria

November 14, 2025

First Posted (Estimated)

November 18, 2025

Study Record Updates

Last Update Posted (Actual)

November 21, 2025

Last Update Submitted That Met QC Criteria

November 18, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • RCS05022024

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Maybe I will decide later.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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