Morbidly obese individuals with impaired fasting glucose have a specific pattern of insulin secretion and sensitivity: effect of weight loss after bariatric surgery.
BACKGROUND
Obesity is often associated with hyper-secrection of insulin. Impaired fasting glucose (IFG) has recently been redefined as a fasting plasma glucose of 5.6-6.9 mmol/L. The aim of this study was to determine whether changes in insulin secretion in morbidly obese persons also commence with normal serum glucose levels.


METHODS
32 morbidly obese subjects were studied before and after bariatric surgery. Measurements were made of glucose tolerance (K(G)), insulin sensitivity (SI), first-phase insulin release and the disposition index (DI) from a frequently sampled intravenous glucose tolerance test.


RESULTS
In morbidly obese subjects, the SI (P<0.01), DI (P<0.01) and first-phase insulin release (P<0.02) started changing with serum glucose levels considered to be normal (5.00-5.28 mmol/L). K(G) showed a clear slope according to the baseline glycemia status (P<0.05), and it was significantly related with the DI, both before (r=0.76, P<0.001) and after (r=0.57, P=0.002) surgery. Following surgery, all the variables significantly associated with insulin secretion and insulin sensitivity recovered significantly. The most significant changes occurred in morbidly obese individuals with IFG.


CONCLUSIONS
Morbidly obese subjects show slopes of insulin sensitivity and insulin secretion in accordance with their baseline serum glucose levels. The fall in first-phase insulin release begins when serum glucose values are considered normal. Morbidly obese persons with the IFG phenotype have a specific pattern of insulin sensitivity and insulin secretion. K(G) clearly discriminates the clinical phenotypes, depending on baseline serum glucose levels.
García-Fuentes
Eduardo
E
Fundación IMABIS, Málaga, Spain. edugf1@eresmas.com
García-Almeida
Jose Manuel
JM
García-Arnés
Juan
J
Rivas-Marín
Jose
J
Gallego-Perales
Jose Luis
JL
González-Jiménez
Belén
B
Cardona
Isabel
I
García-Serrano
Sara
S
Garriga
M José
MJ
Gonzalo
Montserrat
M
de Adana
M Sol Ruiz
MS
Soriguer
Federico
F
D000293:Adolescent; D000328:Adult; D050110:Bariatric Surgery; D001786:Blood Glucose / Q000378:metabolism*; D016022:Case-Control Studies; D005215:Fasting / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D018149:Glucose Intolerance / Q000097:blood* / Q000150:complications* / Q000601:surgery; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood* / Q000150:complications* / Q000601:surgery; D015431:Weight Loss / Q000502:physiology
D001786:Blood Glucose; D007328:Insulin