Effect of Vitamin D Supplementation on Metabolic Parameters in Patients With Type 2 Diabetes and Vitamin D Deficiency (VITD-DM2)

March 9, 2026 updated by: Maria Eugenia Ruiz Diaz Narvaez, Faculty of Medical Sciences, Clinical Hospital

Effect of Vitamin D Administration on Metabolic Parameters in Patients With Type 2 Diabetes and Vitamin D Deficiency: Experience From the Endocrinology Department of the Hospital de Clínicas (FCM/UNA) and Private Practice

The goal of this clinical study is to learn whether vitamin D supplementation improves metabolic control in adults with type 2 diabetes mellitus who have vitamin D deficiency.

The main questions it aims to answer are:

Does vitamin D supplementation improve fasting glucose and glycated hemoglobin (HbA1c) levels in patients with type 2 diabetes and vitamin D deficiency? Does vitamin D supplementation increase serum vitamin D concentrations in these patients?

Researchers will evaluate metabolic parameters before and after vitamin D supplementation to assess changes associated with correction of vitamin D deficiency.

Participants will:

Receive oral vitamin D supplementation (100,000 IU once monthly) for three months Have fasting glucose, HbA1c, body mass index (BMI), and serum vitamin D levels measured at baseline and after three months of supplementation.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Vitamin D deficiency is highly prevalent among individuals with type 2 diabetes mellitus and has been associated with alterations in glucose metabolism, insulin resistance, and systemic inflammation. Several studies suggest that vitamin D may play a role in pancreatic beta-cell function and insulin sensitivity; however, evidence regarding the metabolic effects of vitamin D supplementation in patients with diabetes remains inconsistent.

The aim of this study was to evaluate changes in metabolic parameters after correction of vitamin D deficiency in adults with type 2 diabetes mellitus.

This longitudinal single-arm interventional study included 119 consecutive adult patients with type 2 diabetes mellitus and confirmed vitamin D deficiency. Patients with conditions that could interfere with vitamin D metabolism or absorption, including chronic kidney disease, intestinal malabsorption syndromes, and pregnancy, were excluded.

Participants received oral cholecalciferol supplementation at a dose of 100,000 IU once monthly for three months. Clinical and biochemical parameters were evaluated at baseline and after the intervention period. Measurements included fasting glucose, glycated hemoglobin (HbA1c), body mass index (BMI), and serum vitamin D concentrations.

The study aimed to assess changes in metabolic control following vitamin D supplementation and to explore the potential role of correcting vitamin D deficiency in patients with type 2 diabetes mellitus.

Study Type

Interventional

Enrollment (Actual)

119

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

  • Paraguay
    • Central Department
      • San Lorenzo, Central Department, Paraguay, 2169
        • Hospital de Clínicas, Facultad de Ciencias Médicas, Universidad Nacional de Asunción

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:

  • Adults (≥18 years) of both sexes.
  • Diagnosis of type 2 diabetes mellitus (T2DM).
  • Patients treated at the Endocrinology Service of the Hospital de Clínicas, Facultad de Ciencias Médicas, Universidad Nacional de Asunción (FCM-UNA), or in private clinical practice between May and September 2024.
  • Serum 25-hydroxyvitamin D [25(OH)D] deficiency < 30 ng/mL.
  • Participants who adhered to the prescribed vitamin D supplementation for a period of three months.

Exclusion Criteria:

  • Patients with intestinal malabsorption disorders (e.g., celiac disease, Crohn's disease, or other disorders affecting calcium absorption).
  • Pregnant women.
  • Patients already taking vitamin D supplementation at the time of study initiation.
  • Patients with chronic kidney disease.
  • Patients with a history of bariatric surgery

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: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Vitamin D supplementation
Participants with type 2 diabetes mellitus and vitamin D deficiency receive oral vitamin D supplementation (cholecalciferol 100,000 IU once monthly) for three months.
Dietary supplement: cholecalciferol (vitamin D3)
Oral cholecalciferol administered at a dose of 100,000 IU once monthly for three months in adults with type 2 diabetes mellitus and vitamin D deficiency.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in glycated hemoglobin (HbA1c)
Time Frame: Baseline and 3 months
Change in glycated hemoglobin (HbA1c) levels after vitamin D supplementation in adults with type 2 diabetes mellitus and vitamin D deficiency
Baseline and 3 months

Collaborators and Investigators

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

Sponsor

Faculty of Medical Sciences, Clinical Hospital

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)

May 7, 2024

Primary Completion (Actual)

September 30, 2024

Study Completion (Actual)

March 31, 2025

Study Registration Dates

First Submitted

March 9, 2026

First Submitted That Met QC Criteria

March 9, 2026

First Posted (Actual)

March 12, 2026

Study Record Updates

Last Update Posted (Actual)

March 12, 2026

Last Update Submitted That Met QC Criteria

March 9, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 392-2024

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be publicly available. Data may be available from the investigators upon reasonable request and subject to institutional and ethical approval.

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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