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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
160
capsules, 20 000IU, twice a week, 6 months duration
University Hospital of North Norway
Tromsø, Norway
insulin secretion and sensitivity as assessed by an hyperglycemic clamp
Time frame: 6 months
intraocular pressure
Time frame: 6 months
telomer length
Time frame: 6 months
25-hydroxyvitamin D and 1,25-dihydroxyvitamin D-levels
Time frame: 6 months
serum calcium, PTH, phosphate
Time frame: 6 months
inflammatory markers and lipids
Time frame: 6 months
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