Effect of Vitamin D Repletion on Insulin Resistance and Systemic Inflammation

Status

Completed

Phases

Phase 2

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01354964

Enrollment

Registered

2011-05-17

Start date

2009-03-13

Completion date

2015-09-03

Last updated

2020-11-02

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Insulin Resistance

Keywords

Glucose Metabolism Disorders, Insulin Resistance, Endocrine System, Vitamin D

Brief summary

The purpose of this research is to study the effects of Vitamin D supplementation on the body's response to insulin (a hormone that controls blood sugar), on inflammation, and on specific cells and processes in fat tissue.

Detailed description

Over the last several years, studies have shown that low vitamin D levels may increase risk of developing Type 2 Diabetes. The investigators will administer vitamin D3 (cholecalciferol) to non-diabetic, insulin resistant subjects with vitamin D deficiency (total vitamin D levels \<20 ng/ml) to increase the level of vitamin D3. The investigators will study the effects of increased Vitamin D on insulin action, adipose tissue inflammation, and on certain cells and processes in fat tissue. Investigators will study participants with a procedure called a pancreatic clamp study. During the clamp procedure, glucose (a sugar) and insulin (a hormone produced in the pancreas that regulates the amount of glucose in the blood) are infused with an intravenous catheter, and blood samples are collected periodically throughout the procedure to measure blood sugar levels and the levels of several hormones that are found in the body and are related to glucose metabolism. Adipose tissue inflammation will be measured using the following inflammatory markers: IL-6, PAI-1, TNF-alpha, and iNOS.

Interventions

DRUGVitamin D

DRUGPlacebo

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

ALL

Age

21 Years to 75 Years

Healthy volunteers

Yes

Inclusion criteria

* Serum 25(OH)D\<20ng/ml * Insulin Resistant based on HOMA-IR score of \>3 * Able and willing to provide informed consent * BMI 20-35

Exclusion criteria

* HIV/AIDS * History of any cancer * Sarcoidosis * Alcohol or substance abuse * Cushing's syndrome * Primary hyperparathyroidism * Nephrolithiasis * Pregnancy or breastfeeding * Regular visits to a tanning salon * Hypercalcemia or hypocalcemia * Untreated or uncontrolled hypertension * Any chronic illness requiring medication, other than arthritis, hypertension and hyperlipidemia

Design outcomes

Primary

Measure	Time frame	Description
Percent Change in Hepatic Insulin Sensitivity	2nd clamp visit (after up to 3 months) and 3rd clamp visit (after up to 6 months)	Endogenous glucose production (EGP) was assessed at each study visit to evaluate hepatic insulin sensitivity. Percent change between the EGP at baseline and second visit (after treatment for up to 3 months with Vitamin D to reach a target level of ≥30 ng/ml), and baseline and third visits (after treatment for up to 6 months with Vitamin D in order to reach a target level of ≥50 ng/ml) will be calculated.

Secondary

Measure	Time frame	Description
Percent Change in Peripheral Glucose Uptake	2nd clamp visit (up to 3 months) and 3rd clamp visit (up to 6 months)	The rate of glucose uptake to determine peripheral insulin sensitivity was measured using the rate of disappearance (Rd) of glucose at each study visit. Percent change between the Rd at baseline and second visit (after treatment with Vitamin D for up to 3 months to target level of ≥30 ng/ml), and baseline and third visits (after treatment with Vitamin D for up to 6 months to target level of ≥50 ng/ml) will be calculated.
Evaluated Expression of Pro-inflammatory Gene TNF-α	2nd clamp visit (up to 3 months) and 3rd clamp visit (up to 6 months)	Adipose tissue macrophages will be isolated from subcutaneous abdominal adipose tissue, and will be quantified by fluorescence activated cell sorting (FACS) analysis. TNF-α gene expression will be examined by real-time (rt-PCR) and will provide a measure of macrophage activation at baseline, at 2nd study visit (after treatment with Vitamin D to a goal level of ≥30 ng/ml), and at 3rd study visit (goal Vitamin D level of ≥50 ng/ml). The mRNA copy number is then compared with a reference gene copy number (5 commonly used house keeping genes \[HKGs\]) as a ratio, which is a measure of relative gene expression.
Evaluated Expression of Pro-inflammatory Gene IL-6	2nd clamp visit (up to 3 months) and 3rd clamp visit (up to 6 months)	Adipose tissue macrophages will be isolated from subcutaneous abdominal adipose tissue, and will be quantified by fluorescence activated cell sorting (FACS) analysis. IL-6 gene expression will be examined by real-time (rt-PCR) and will provide a measure of macrophage activation at baseline, at 2nd study visit (after treatment with Vitamin D to a goal level of ≥30 ng/ml), and at 3rd study visit (goal Vitamin D level of ≥50 ng/ml). The mRNA copy number is then compared with a reference gene copy number (5 commonly used house keeping genes \[HKGs\]) as a ratio, which is a measure of relative gene expression.
Evaluated Expression of Pro-inflammatory Gene iNOS	2nd clamp visit (up to 3 months) and 3rd clamp visit (up to 6 months)	Adipose tissue macrophages will be isolated from subcutaneous abdominal adipose tissue, and will be quantified by fluorescence activated cell sorting (FACS) analysis. iNOS gene expression will be examined by real-time (rt-PCR) and will provide a measure of macrophage activation at baseline, at 2nd study visit (after treatment with Vitamin D to a goal level of ≥30 ng/ml), and at 3rd study visit (goal Vitamin D level of ≥50 ng/ml). The mRNA copy number is then compared with a reference gene copy number (5 commonly used house keeping genes \[HKGs\]) as a ratio, which is a measure of relative gene expression.
Evaluated Expression of Pro-inflammatory Gene PAI-1	2nd clamp visit (up to 3 months) and 3rd clamp visit (up to 6 months)	Adipose tissue macrophages will be isolated from subcutaneous abdominal adipose tissue, and will be quantified by fluorescence activated cell sorting (FACS) analysis. PAI-1 gene expression will be examined by real-time (rt-PCR) and will provide a measure of macrophage activation at baseline, at 2nd study visit (after treatment with Vitamin D to a goal level of ≥30 ng/ml), and at 3rd study visit (goal Vitamin D level of ≥50 ng/ml). The mRNA copy number is then compared with a reference gene copy number (5 commonly used house keeping genes \[HKGs\]) as a ratio, which is a measure of relative gene expression.

Countries

United States

Participant flow

Participants by arm

Arm	Count
Vitamin D Participants received weekly oral vitamin D drops using a weight-based calculated dosage for up to six months. .	11
Placebo Participants received weekly oral placebo drops (similar in taste and appearance to vitamin D) for up to six months.	8
Total	19

Withdrawals & dropouts

Period	Reason	FG000	FG001
Overall Study	IV access issues	1	1
Overall Study	Lost to Follow-up	2	0
Overall Study	Physician Decision	1	0

Baseline characteristics

Characteristic	Total	Placebo	Vitamin D
Age, Continuous	44.2 years STANDARD_DEVIATION 11.1	47.3 years STANDARD_DEVIATION 11.5	42.0 years STANDARD_DEVIATION 10.7
Evaluated expression of pro-inflammatory gene IL-6 in macrophages	0.05 Ratio of mRNA copy numbers (IL-6/5HKGs) STANDARD_DEVIATION 0.05	0.04 Ratio of mRNA copy numbers (IL-6/5HKGs) STANDARD_DEVIATION 0.05	0.06 Ratio of mRNA copy numbers (IL-6/5HKGs) STANDARD_DEVIATION 0.05
Evaluated expression of pro-inflammatory gene iNOS in macrophages	0.007 Ratio of mRNA copy numbers (iNOS/5HKGs) STANDARD_DEVIATION 0.007	0.006 Ratio of mRNA copy numbers (iNOS/5HKGs) STANDARD_DEVIATION 0.005	0.007 Ratio of mRNA copy numbers (iNOS/5HKGs) STANDARD_DEVIATION 0.008
Evaluated expression of pro-inflammatory gene PAI-1 in macrophages	0.03 Ratio of mRNA copy numbers (PAI-1/5HKGs) STANDARD_DEVIATION 0.03	0.04 Ratio of mRNA copy numbers (PAI-1/5HKGs) STANDARD_DEVIATION 0.03	0.03 Ratio of mRNA copy numbers (PAI-1/5HKGs) STANDARD_DEVIATION 0.03
Evaluated expression of pro-inflammatory gene TNF-α in macrophages	0.04 Ratio of mRNA copy numbers (TNF-α/5HKGs) STANDARD_DEVIATION 0.03	0.02 Ratio of mRNA copy numbers (TNF-α/5HKGs) STANDARD_DEVIATION 0.02	0.05 Ratio of mRNA copy numbers (TNF-α/5HKGs) STANDARD_DEVIATION 0.03
Hepatic Insulin Sensitivity	1.20 mg/kg/min STANDARD_DEVIATION 0.63	1.10 mg/kg/min STANDARD_DEVIATION 0.64	1.28 mg/kg/min STANDARD_DEVIATION 0.65
Peripheral Glucose Uptake	6.29 mg/kg/min STANDARD_DEVIATION 1.74	6.71 mg/kg/min STANDARD_DEVIATION 2.33	5.99 mg/kg/min STANDARD_DEVIATION 1.18
Race/Ethnicity, Customized Asian	0 Participants	0 Participants	0 Participants
Race/Ethnicity, Customized Black or African American	12 Participants	5 Participants	7 Participants
Race/Ethnicity, Customized Hispanic or Latino	2 Participants	0 Participants	2 Participants
Race/Ethnicity, Customized Other	0 Participants	0 Participants	0 Participants
Race/Ethnicity, Customized White Non-Hispanic	5 Participants	3 Participants	2 Participants
Region of Enrollment United States	19 participants	8 participants	11 participants
Sex: Female, Male Female	6 Participants	2 Participants	4 Participants
Sex: Female, Male Male	13 Participants	6 Participants	7 Participants

Adverse events

Event type	EG000 affected / at risk	EG001 affected / at risk
deaths Total, all-cause mortality	0 / 11	0 / 8
other Total, other adverse events	1 / 11	0 / 8
serious Total, serious adverse events	1 / 11	0 / 8

Outcome results

Primary

Percent Change in Hepatic Insulin Sensitivity

Endogenous glucose production (EGP) was assessed at each study visit to evaluate hepatic insulin sensitivity. Percent change between the EGP at baseline and second visit (after treatment for up to 3 months with Vitamin D to reach a target level of ≥30 ng/ml), and baseline and third visits (after treatment for up to 6 months with Vitamin D in order to reach a target level of ≥50 ng/ml) will be calculated.

Time frame: 2nd clamp visit (after up to 3 months) and 3rd clamp visit (after up to 6 months)

Population: Hepatic insulin sensitivity was measured in 7 (out of 11) participants in the Vitamin D group and in 7 (out of 8) participants in the placebo group at the 3rd study visit due to loss to follow up, withdrawal, or difficulties in obtaining IV access.

Arm	Measure	Group	Value (MEAN)	Dispersion
Vitamin D	Percent Change in Hepatic Insulin Sensitivity	Percent change between baseline and 2nd visit	-19.2 percent change	Standard Error 11.6
Vitamin D	Percent Change in Hepatic Insulin Sensitivity	Percent change between baseline and 3rd visit	-33.66 percent change	Standard Error 7.5
Placebo	Percent Change in Hepatic Insulin Sensitivity	Percent change between baseline and 2nd visit	5.8 percent change	Standard Error 22.5
Placebo	Percent Change in Hepatic Insulin Sensitivity	Percent change between baseline and 3rd visit	113.7 percent change	Standard Error 65.5

Secondary

Evaluated Expression of Pro-inflammatory Gene IL-6

Adipose tissue macrophages will be isolated from subcutaneous abdominal adipose tissue, and will be quantified by fluorescence activated cell sorting (FACS) analysis. IL-6 gene expression will be examined by real-time (rt-PCR) and will provide a measure of macrophage activation at baseline, at 2nd study visit (after treatment with Vitamin D to a goal level of ≥30 ng/ml), and at 3rd study visit (goal Vitamin D level of ≥50 ng/ml). The mRNA copy number is then compared with a reference gene copy number (5 commonly used house keeping genes \[HKGs\]) as a ratio, which is a measure of relative gene expression.