Effects of resveratrol on insulin sensitivity, brown adipose tissue and metabolic profile in first-degree relatives of type 2 diabetic patients

There is now a general consensus that the combination of excessive energy
intake and a low capacity to oxidize fat will lead to muscular fat accumulation
and insulin resistance. It is known for many years that physical activity and
diet therapy are the most powerful treatment to combat obesity and insulin
resistance, but it is also known that it is difficult to get people to exercise
and follow diets. A major breakthrough in this field has come from the
nutrition field, with the finding that resveratrol, a natural polyphenolic
compound, could serve as an *caloric restriction mimetic*, as a recent study of
S. Timmers et al. in Cell metabolims (2011) showed that resveratrol mimicked
the effect of caloric restriction in healthy obese man (lowering liver fat
accumulation and increasing fat oxidation, thereby improving metabolic health
in these subjects). These findings were similar to those found earlier in
animal studies, where it was found that resveratrol protected mice from many
detrimental effects of diet-induced obesity. Therefore we would like to
investigate if resveratrol has the same effects in humans at increased risk for
developing type 2 diabetes (first-degree relatives of type 2 diabetics) as it
does in healthy obese man. This information can then be used to develop new
treatment of type 2 diabetes especially with respect to preventive strategies.
Therefore, we would like to investigate whether ResvidaTM can increase
mitochondrial number together with an increased intrinsic activity and whether
this will lead to a better insulin sensitivity in first-degree relatives of
type 2 diabetic patients.
Besides the recently discovered positive effects of resveratrol on the
metabolic complications associated with obesity, resveratrol could also target
obesity itself. Since the rediscovery of functional active brown adipose tissue
in adult humans this tissue has received strong scientific attention. Recent
studies in mice inidcate that the improved metabolism accompanying oral
administration of reseveratrol is associated with increased brown adipose
tissue thermogenesis and high UCP1 and SIRT1 expression.

To examine whether resveratrol supplementation in first-degree relatives of
type 2 diabetic patients improves overall and muscle-specific insulin
sensitivity by affecting mitochondrial fat oxidative capacity. Furthermore, we
are interested is this also affects liver and muscle fat storage and whether
brown adipose tissue activity increases after resveratrol administration.

80 overweight (BMI 27-35 kg/m2) male subjects with family member(s) diagnosed
with type 2 diabetes, aged between 40 and 70 years, who are not engaged in
regular programmed exercise, with glucose clearance rate <350 ml/kg/min will be
recruited of which 24 will be included in a randomized, double blind cross over
design. Each subject will participate in two interventions, in random order,
and separated by a wash-out period of at least 4 weeks. Each intervention
includes a 30 days suppelementation with resveratrol or placebo. Before the
start of the study, subjects will be screened to assess eligibility, which will
include a medical questionnaire, and a fasted blood sample.
On day 0, subjects will come to the university for withdrawal of a fasted blood
sample and a measurement of body weight. Hereafter, heart rate and blood
pressure will be checked and an ECG will be made by an experienced physician.
Finally a measurement to determine body composition and fat content is executed
(DEXA scan).
Thereafter, subjects can go home and they will receive enough capsules for the
first week of the intervention. Additional blood samples will be drawn on a
weekly basis as well as measurements of body weight (day 7, 14, 21). During
these weekly visits, subjects will receive enough capsules for the next week.
On day 27, subjects will report to the university for a maximal aerobic
capacity test under the supervision of a physician. An ECG will be made during
the cycling test. On day 29, hart function will be measured by
echocardiography, and in vivo mitochondrial function and liver fat content will
be measured with MR spectroscopy. Thereafter, subjects will stay in the
respiration chamber for 12 hours (evening day 29 and night day 29) during which
their energy expenditure and fat oxidation will be measured. On day 30 in the
morning, subjects will leave the respiration chamber, and a fasting blood
sample will be drawn. An ECG will be made and blood pressure and heart rate
will be measured. Then, fat content in the heart will be measured by MR
spectroscopy and a muscle biopsy will be taken. Hereafter, the insulin
sensitivity measurement will be started to determine overall and muscle and
liver specific insulin sensitivity. After the test, a second muscle biopsy will
be taken.
9 subjects will also participatie in the brown adipose tissue part op this
study. They will recieve resveratrol (or placebo) for 33 days and come to the
university on day 33 for a FDG PET/CT scan after mild cold exposure.

Subjects will be asked to take two pills of resveratrol 75 mg, or placebo,
twice daily (lunch and diner), for 30 days, which will be randomized.
Resveratrol (resvidaTM) is a food supplement and is regulated in the body as a
food component. ResvidaTM and placebo are provided by DSM Nutritional Products
Ltd. For the resveratrol product, the maximal approved daily dose in humans is
150 mg/day. For higher doses the safety concerns are not yet investigated.
Therefore, we have chosen to supplement the subjects with a dose of 150 mg/day
spread out over two doses of 75 mg twice a day with lunch and diner.

Before the start of the study, subjects will be screened to access eligibility
which will include a medical questionnaire, measurement of body weight and OGTT
wil be executed to determine glucose clearance (as marker for insulin
sensitivity). A fasted bloodsample will also be drawn (duration: 3 hours).
Thereafter, they will be randomized and undergo two intervention periods of 30
days separated by a wash-out period of at least 4 weeks. The subjects will come
to the University 6 times (day 0, 7, 14, 21, 27, 29). During these visits at
the University, a bloodsample will be taken weekly as well as a weekly
measurement of body weight (day 0, 7, 14, 21). On day 0 also a DEXA scan is
executed in order to determine body composition and body fat. A maximal aerobic
capacity test will be performed (day 27) and heart function will be measured by
echocardiography, in vivo mitochondrial function and liver fat content will be
measured with MRS (day 29). In addition, subjects will stay in the respiration
chamber for 12 hours (1 evening and night) (day 29-30) after which the fat
content of the heart will be measured by MR spectroscopy (day 30), and a muscle
biopsy will be taken (day 30). Hereafter, the insulin sensitivity test will be
started (day 30). After this test is finished, a second muscle biopsy will be
taken (day 30).

For the subjects that participate in the brown adipose tissue part of the study:
On day 33 an FDG PET/CT scan after mild cold exposure takes place. These
subjects will come to the university 7 times during 4 weeks (day 0, 7, 14, 21,
27, 29 and 33).