Brown Adipose Tissue Activity in Caucasians and South Asians

It is well known that the prevalence and incidence of type 2 diabetes (DM)
varies between ethnic groups. People of South Asian origin in particular have
an increased risk of DM, which is about four times that of people of European
origin. Moreover, The exact explanation for this increased risk is still
unclear. We hypothesize that a still unidentified factor significantly
contributing to the metabolic disbalance in South Asians might be a lower brown
adipose tissue (BAT) activity.
BAT has only recently identified as a possible mean to significantly influence
glucose metabolism. The knowledge of mechanism that influence BAT is still
scare. To our knowledge, there have not been any studies published about BAT
activity among different ethnic groups. The aim of this study is not only to
investigate whether BAT activity differs between South Asians and Caucasians,
but to also reveal more about factors that can actually influence BAT
activity

Main objective:
1) To investigate whether BAT activity differs between South Asians and
Caucasians.

Secondary objectives:
1) To investigate whether sympatic stimulation of BAT differs between South
Asians and Caucasians
2) To investigate the correlation between sympatic stimulation of BAT with BAT
activity itself in South Asians and Caucasians.
3) To investigate the relationship between insulin resistance and BAT activity
in South Asians and Caucasians

Observational design with invasive measurements.

Included subjects will visit the AMC hospital on four occasions.
Visit 1: Informed consent, self-reported ethnicity, medical history, vital
signs, explanation of study procedures, laboratory measurements. Total blood
drawn: 22 ml.
Visit 2: Infusion of I-123 metaiodobenzylguanidine (MIBG) PET scan
(scintigraphy)
Visit 3 (24 hours after visit 2): second MIBG PET scan (no new infusion of
MIBG) and euglycemic clamp
Visit 4: 18F-fluorodeoxyglucose (FDG) PET-CT scan

During the entire study, a total of 122 ml will be drawn (22 ml during visit 1
and 100 ml during the euglycemic clamp).

The resulting dose from the low dose CT scan + the radioactive tracers is 9.0
mSv. There is no direct benefit for the volunteers. This study will provide new
insights into ethnic differences in the pathofysiology of DM, which is needed
for the efficient prevention and treatment of DM. In addition, this study will
widen our knowledge about the mechanisms that influence BAT activity. BAT
activity has only recently been identified as a possible mean to significantly
influence glucose metabolism, and knowledge about factors influencing BAT
activity is still scarce.