Vitamin D AND Glucose Handling Evaluated by Glucose Clamp

Vitamin D AND Cardiovascular Disease

Status

Completed

Phases

Phase 2

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00809744

Acronym

D-clamp

Enrollment

160

Registered

2008-12-17

Start date

2008-11-30

Completion date

2010-12-31

Last updated

2011-11-03

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

Conditions

Insulin Sensitivity, Intraocular Pressure

Brief summary

In this study the investigators want to compare glucose handling (insulin secretion and insulin sensitivity) in 100 persons with low and 50 persons with normal-high levels of vitamin D, using a hyperglycemic clamp technique, were sugar is given intravenously for 3 hours in order to keep the blood sugar level at 10 mmol/L. Those with low vitamin D levels will be randomized to treatment with vitamin D3 (cholecalciferol) 40 000 IU/week or placebo for 6 months before a new clamp is performed. The study hypothesis is that persons with low vitamin D levels have impaired glucose handling which might be improved by vitamin D supplementation.

Interventions

DRUGcholecalciferol

capsules, 20 000IU, twice a week, 6 months duration

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Masking

QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

ALL

Age

30 Years to 75 Years

Healthy volunteers

Inclusion criteria

* generally: Subjects are recruited from the 6th Tromsø Study * cases: serum 25-hydroxyvitamin D-levels below the 10 percentile; low levels confirmed with new serum analyses. * controls: serum 25-hydroxyvitamin D levels 80-95 percentile, normal-high levels confirmed with new serum analyses.

Exclusion criteria

* diabetes * myocardial infarction or apoplexia * active cancer during last 5 years * history of kidney stone * pregnancy or premenopausal without safe anticonception * primary hyperparathyroidism * systolic blood pressure \>175 or diastolic blood pressure \>105

Design outcomes

Primary

Measure	Time frame
insulin secretion and sensitivity as assessed by an hyperglycemic clamp	6 months
intraocular pressure	6 months

Secondary

Measure	Time frame
telomer length	6 months
25-hydroxyvitamin D and 1,25-dihydroxyvitamin D-levels	6 months
serum calcium, PTH, phosphate	6 months
inflammatory markers and lipids	6 months

Countries

Norway

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026