Herbal Preparation and Glucose Homeostasis
Condition: Glucose Tolerance; Lipid Homeostasis; Vascular Function; Inflammation
MeSH terms: Inflammation
Study type: Interventional

Summary: 
      Rationale: The incidence of obesity and type 2 diabetes (T2D) is increasing rapidly and
      accounts for a considerable part of health care costs. Herbal supplements are used in many
      cultures for the prevention and treatment of many different conditions. Due to lack of
      scientific proof, the application in western cultures are minimal. Animal studies have shown
      that many constituents of such herbal supplements may have beneficial effects on several
      important parameters known to be affected in T2D. Still, no scientific proof in humans is
      available. We therefore aim to investigate the effect of 4-week herbal supplementation on
      glucose metabolism, lipid metabolism, vascular function and inflammation in subjects with
      increased fasting glucose levels or a decreased glucose tolerance.

      Objective: The primary objectives are to investigate if 4-week herbal supplementation in
      subjects with increased fasting glucose levels or a decreased glucose tolerance has a
      positive effect on blood glucose levels and glucose tolerance. The secondary objectives are
      to investigate if 4-week herbal supplementation in subjects with increased fasting glucose
      levels or a decreased glucose tolerance has a positive effect on triglycerides (TG), total
      cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL) levels,
      inflammation, adipose tissue and white blood cell gene-expression and AIX both fasted and
      during an OGTT test.

      Study design: This study is a randomized, double-blind, placebo controlled cross-over trial
      in which two different treatments will be evaluated e.g. an intervention with the herbal
      mixture and a placebo. Each person will obtain both treatments in random order for four weeks
      with a wash out period of four weeks in-between. Fasting blood samples will be collected and
      subjects will receive a OGTT, paralleled by a PWA before and after 4-week supplementation.

      Furthermore, after 4-week supplement intake we will collect a urine sample and collect an
      adipose tissue biopsy. The whole trial will last three months.

      Study population: 26 overweight males and females 50-75yrs old with an increased fasting
      glucose or with an impaired glucose tolerance.

      Intervention: Two intervention periods of 4-weeks in which participants will take three times
      a day a supplement of 500mg herbal or placebo.

      Main study parameters/endpoints: Fasting blood glucose levels, glucose tolerance as
      determined by an oral glucose tolerance test (OGTT), AIX, triglycerides (TG), total
      cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL) levels, PWA,
      adipose tissue an white blood cell gene expression and markers of inflammation .

      Nature and extent of the burden and risks associated with participation, benefit and group
      relatedness: Subjects that will participate in the study will invest a total of 16.5 hours.
      Blood collection by vena punctures/insertion of the venflon and the collection of an adipose
      tissue biopsy can occasionally cause a local hematoma or bruise and some participants may
      report pain or discomfort. The herbal supplements contain small amounts St. John's wort,
      which may affect the function of liver enzymes. We will therefore monitor liver function
      parameters during the supplementation period. Furthermore, subjects are excluded if they use
      medication known to be affected by St. John's wort. Participant will donate 284ml of blood,
      dispersed over 12 weeks.
    


Intervention name(s): herbal supplement; placebo supplement
Intervention type(s): Dietary Supplement; Other
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention