Insulin sensitivity of splanchnic and peripheral adipose tissue in vivo in morbidly obese man

Abstract

Epidemiologic studies demonstrate an association between increased waist to hip ratio ([WHR] android obesity, central obesity) and diabetes mellitus in man. To study the relative insulin sensitivity of splanchnic versus peripheral adipose tissue, portal vein catheterization via the collapsed umbilical vein was performed in 14 morbidly obese subjects at the time of surgery. Catheters were also placed in a peripheral artery and antecubital vein such that simultaneous arterio-venous (A-V) differences (glycerol, free fatty acids [FFA], and lactate) could be determined. After two baseline samples obtained 3 minutes apart, 25 g intravenous (IV) glucose (14 subjects) was administered over a 2-minute period, with samples being obtained every 5 minutes for 30 additional minutes. Arterial plasma glycerol levels decreased from 173.9 ± 17.4 μmol/L at baseline to 89.1 ± 7.6 μmol/L at 30 minutes ( P < .01). Peripheral and splanchnic A-V glycerol differences were similar at baseline, but within 10 minutes after glucose administration the difference across the splanchnic area decreased by 52% and remained significantly less than that across the periphery ( P < .01). Despite a 49% decrease in arterial plasma glycerol level, plasma FFA level decreased only 18.3% over the 30-minute period (942 ± 74.8 to 770.0 ± 76 μmol/L, NS). These studies in morbidly obese man (glycerol data) indicate a greater insulin sensitivity of splanchnic adipose tissue than of peripheral adipose tissue. Thus hypertrophy of fat in the splanchnic area might be an expected consequence of the hyperinsulinemia associated with insulin-resistant states.