Sex differences in African-Americans regarding sensitivity to insulin's glucoregulatory and antilipolytic actions

• Published in: Diabetes care Vol. 22; no. 1; pp. 71 - 77
• Main Authors: Sumner, A E, Kushner, H, Sherif, K D, Tulenko, T N, Falkner, B, Marsh, J B
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Diabetes Association 01.01.1999
• Subjects: Adult; African Americans; Analysis of Variance; Biological and medical sciences; Black or African American; Black People; Blood Glucose - drug effects; Blood Glucose - metabolism; Body fat; Cohort Studies; Diabetes; Fatty acids; Female; Gender differences; Glucose; Glucose Clamp Technique; Glucose Tolerance Test; Health sciences; Homeostasis; Humans; Hyperinsulinism; Infusions, Intravenous; Insulin; Insulin - administration & dosage; Insulin - pharmacology; Insulin - physiology; Laboratories; Lipolysis - drug effects; Longitudinal Studies; Male; Medical sciences; Metabolic Clearance Rate; Metabolic diseases; Obesity; Philadelphia; Plasma; Regression Analysis; Research design; Sex Characteristics; Women; United States; North America; America; Philadelphia; Human; Obesity; Pancreatic hormone; Pathophysiology; Glucose clamp technique; Nutrition disorder; Sex; Lipids; Glucose tolerance test; Free fatty acid; Insulin; Blood plasma; Target tissue resistance; Hormonal regulation; Adult; Nutritional status; Comparative study; Glycemia
• ISSN: 0149-5992; 1935-5548
• DOI: 10.2337/diacare.22.1.71

Sex differences in African-Americans regarding sensitivity to insulin's glucoregulatory and antilipolytic actions. A E Sumner , H Kushner , K D Sherif , T N Tulenko , B Falkner and J B Marsh Institute for Women's Health, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania, USA. annes@intra.niddk.nih.gov Abstract OBJECTIVE: The purpose of this study was to determine if there are sex differences in African-Americans regarding the effect of obesity on sensitivity to insulin as a glucoregulatory and antilipolytic hormone. RESEARCH DESIGN AND METHODS: Data from study participants, 127 nondiabetic African-Americans (mean age 32 +/- 4 years), included anthropometric measurements, an oral glucose tolerance test (OGTT), a 2-h euglycemic-hyperinsulinemic clamp, and a fasting triglyceride level. Sensitivity to insulin as a glucoregulatory hormone was determined by M/FFM, where M is the mean glucose infusion rate during the second hour of the clamp and FFM is fat-free mass. Sensitivity to insulin's antilipolytic action was assessed during the OGTT by the percent suppression of free fatty acid (FFA) concentrations between 0 and 120 min. The higher the suppression of FFAs, the greater the sensitivity to insulin's antilipolytic action. RESULTS: The participants were classified by BMI into three groups: nonobese (31 men, 24 women), obese (17 men, 14 women), and severely obese (12 men, 29 women). The women had higher percentages of body fat (P < 0.001), and the men had greater FFM (P < 0.001). The M/FFM values for men versus women in each BMI group were nonobese, 8.8 +/- 2.8 vs. 10.8 +/- 4.4; obese, 7.2 +/- 3.4 vs. 8.5 +/- 3.4; and severely obese, 4.7 +/- 2.1 vs. 6.1 +/- 2.2. The difference between the BMI groups was significant (P < 0.001), as was the difference between men and women (P < 0.01). In addition, there was a significant sex difference in percent suppression of FFAS (P < 0.001). The men and women had similar fasting insulin and FFA concentrations; however, in the men only, the percent suppression of FFA declined with increasing obesity (nonobese, 83 +/- 15%; obese, 73 +/- 18%; and severely obese, 69 +/- 19%; P = 0.02). The women in all three BMI groups had lower FFA levels of 86-88%. CONCLUSIONS: Obese African-American men and women are resistant to insulin as a glucoregulatory hormone, but only obese men are resistant to insulin's antilipolytic action; obese African-American women are sensitive to insulin's antilipolytic action. The combined presence of sensitivity to insulin's antilipolytic action with resistance to insulin's glucoregulatory action in obese African-American women may contribute to their high prevalence of obesity and type 2 diabetes.