Can Vitamin D3 Improve Cognitive Function in Individuals With Type 2 Diabetes? (THINK-D)
Condition: Diabetes; Executive Dysfunction
MeSH terms: Diabetes Mellitus
Intervention: Cholecalciferol; Cholecalciferol
Intervention description: Participants will take randomly assigned high dose cholecalciferol once weekly for three months; Participants will take randomly assigned active comparator cholecalciferol once weekly for three months
Intervention MeSH terms: Vitamin D; Ergocalciferols; Cholecalciferol; Vitamins
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Enrollment: 56.0
Sex: All
Minimum age: 18 Years
Maximum age: 75 Years
Healthy volunteers: No
Keywords: Diabetes; Cognition; Functioning

Summary:

      Diabetes increases the risk of cognitive dysfunction. The incidence of dementia is 1.5 to 2.5
      times higher in persons with diabetes than the general population. There is evidence that
      cognitive decline significantly impacts the ability to self-manage diabetes. Strategies to
      prevent cognitive decline in persons with diabetes has not been well studied. A recent study
      reported that in persons who had vitamin D deficiency, the risk for all-cause dementia and
      Alzheimer's was doubled. Vitamin D receptors are located in the brain and deficiency of
      vitamin D has been reported to negatively affect the development of brain. Therefore,
      providing vitamin D supplementation to improve cognitive function is worthy of study. The
      investigators propose a small, randomized controlled trial to determine the effects of
      vitamin D3 supplementation in persons with type 2 diabetes who have symptoms of cognitive
      impairment. Persons will be randomized to receive either weekly vitamin D3 supplementation
      (50,000 IUs) or a matching comparator (5000 IUs) for a period of three months. The study aims
      are to determine (1) the effect of vitamin D3 supplementation on cognitive function and (2)
      the effect of vitamin D3 supplementation on diabetes self-management. A sample of persons
      with type 2 diabetes (n=62), who have a subjective complaint of a cognitive dysfunction or
      scoring at least one standard deviation below normal on a cognitive functioning screening
      test, have vitamin D levels less 30 ng/ml, are not depressed (as this impacts cognitive
      function), and do not have severe diabetes complication will be recruited. Participants will
      be phone screened and complete two baseline visits prior to randomization. They will then
      have phone call and follow-up visits to assess (1) cognitive function using standardized
      tests to assess for executive function (2) serum measurements (HBA1c, fasting glucose,
      vitamin D levels, and cardiometabolic profile) and (3) surveys to assess cognitive function
      as well as self-management behaviors.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Women and men aged 18 to 75 years

          -  Have type 2 diabetes

          -  Having a subjective complaint of a cognitive dysfunction or scoring at least one
             standard deviation below normal on a cognitive functioning screening test

          -  Vitamin D level as measured by 25-hydroxyvitamin D (25-OH D) < 32 ng/mL

          -  Under the care of a healthcare provider

          -  Systolic blood pressure ≤160 and diastolic blood pressure ≤100

        Exclusion Criteria:

          -  Persons with malabsorption problems (e.g., crohn's disease)

          -  Hypercalcemia

          -  Supplementation other than a daily multivitamin

          -  Severe complications of diabetes (i.e., amputation, blindness, and dialysis)

          -  Concomitant use of steroids

          -  GFR < 60

          -  Creatinine > 1.2

          -  Significant depressive symptoms

          -  Having a history of bipolar depression, psychotic disorders, loss of consciousness
             greater than 5 minutes, or a current alcohol or substance use disorder

          -  Other serious medical conditions deemed significant by the PI or medical monitor

          -  Concomitant use of cholinesterase inhibitors

          -  Concomitant use of anxiolytics, kava kava, St. John's Wort, or Ginkgo Biloba

          -  Pregnancy

          -  HbA1c >13%