Changes in subcutaneous fat cell volume and insulin sensitivity after weight loss.
OBJECTIVE
Large subcutaneous fat cells associate with insulin resistance and high risk of developing type 2 diabetes. We investigated if changes in fat cell volume and fat mass correlate with improvements in the metabolic risk profile after bariatric surgery in obese patients.


METHODS
Fat cell volume and number were measured in abdominal subcutaneous adipose tissue in 62 obese women before and 2 years after Roux-en-Y gastric bypass (RYGB). Regional body fat mass by dual-energy X-ray absorptiometry; insulin sensitivity by hyperinsulinemic-euglycemic clamp; and plasma glucose, insulin, and lipid profile were assessed.


RESULTS
RYGB decreased body weight by 33%, which was accompanied by decreased adipocyte volume but not number. Fat mass in the measured regions decreased and all metabolic parameters were improved after RYGB (P < 0.0001). Whereas reduced subcutaneous fat cell size correlated strongly with improved insulin sensitivity (P = 0.0057), regional changes in fat mass did not, except for a weak correlation between changes in visceral fat mass and insulin sensitivity and triglycerides. The curve-linear relationship between fat cell size and fat mass was altered after weight loss (P = 0.03).


CONCLUSIONS
After bariatric surgery in obese women, a reduction in subcutaneous fat cell volume associates more strongly with improvement of insulin sensitivity than fat mass reduction per se. An altered relationship between adipocyte size and fat mass may be important for improving insulin sensitivity after weight loss. Fat cell size reduction could constitute a target to improve insulin sensitivity.
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Daniel P
DP
Andersson
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Daniel
D
Eriksson Hogling
Department of Surgery, Karolinska Institutet, Ersta Hospital, Stockholm, Sweden.
Anders
A
Thorell
Department of Medicine, Karolinska Institutet, Ersta Hospital, Stockholm, Sweden.
Eva
E
Toft
Department of Medicine, Karolinska Institutet, Ersta Hospital, Stockholm, Sweden.
Veronica
V
Qvisth
Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden.
Erik
E
Näslund
Department of Surgery, Södertälje Hospital, Södertälje, Sweden.
Anders
A
Thörne
Department of Surgery, Karolinska Institutet, Stockholm, Sweden.
Mikael
M
Wirén
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Patrik
P
Löfgren
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Johan
J
Hoffstedt
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Ingrid
I
Dahlman
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Niklas
N
Mejhert
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Mikael
M
Rydén
Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Erik
E
Arner
Department of Medicine, Karolinska Institutet, Stockholm, Sweden peter.arner@ki.se.
Peter
P
Arner
D015502:Absorptiometry, Photon; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D048429:Cell Size; D005260:Female; D015390:Gastric Bypass / Q000379:methods*; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat / Q000378:metabolism; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D009765:Obesity / Q000601:surgery*; D011446:Prospective Studies; D050151:Subcutaneous Fat / Q000166:cytology*; D014280:Triglycerides / Q000097:blood / Q000502:physiology; D015431:Weight Loss / Q000502:physiology
D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; D014280:Triglycerides