African Americans and Caucasian Americans: Differences in Glucocorticoid-Induced Insulin Resistance

Abstract

African Americans are more insulin resistant than Caucasian Americans and this discrepancy cannot be explained by measures of body weight or body composition. The aim of the study was to compare the sensitivity of African Americans and Caucasian Americans to glucocorticoids by measuring glucose and insulin responses to a meal challenge under conditions of placebo and glucocorticoid. A total of 160 healthy or overweight/obese African American and Caucasian American participants completed exercise testing and a liquid meal challenge during separate laboratory visits. Participants were evaluated following treatments with placebo and dexamethasone (4 mg). Main outcome measures were correlation between body composition measures (body mass index, percent body fat, waist circumference) and insulin responses; insulin and glucose responses after a liquid meal challenge; and calculated HOMA. After dexamethasone treatment African Americans were significantly more hyperinsulinemic after a meal as indicated by higher peak insulin (p=0.02) and postprandial insulin areas under the curve (p=0.006) than Caucasians. Additionally, African Americans were more insulin resistant than Caucasian Americans under both placebo and dexamethasone as determined by fasting insulin and HOMA (p=0.05). Waist circumference correlated with post-dexamethasone insulin AUC and HOMA in Caucasian Americans (p<0.05), but none of the body composition measures were predictive of IR for African Americans. African Americans are more sensitive to glucocorticoids (dexamethasone) than Caucasian Americans, as indicated by significantly greater peak insulin and postprandial insulin areas under the curve. The glucocorticoid receptor and its potential interactions with stress may contribute to this ethnic disparity.

stress hormones - obesity - glucocorticoid receptor - adrenal hormones - HOMA

References

• 1 Osei K, Schuster DP. Ethnic differences in secretion, sensitivity, and hepatic extraction of insulin in black and white Americans.  Diabet Med. 1994;  11 755-762
• 2 Arslanian SA, Saad R, Lewy V, Danadian K, Janosky J. Hyperinsulinemia in african-american children: decreased insulin clearance and increased insulin secretion and its relationship to insulin sensitivity.  Diabetes. 2002;  51 3014-3019
• 3 Goran MI, Bergman RN, Cruz ML, Watanabe R. Insulin resistance and associated compensatory responses in african-american and Hispanic children.  Diabetes Care. 2002;  25 2184-2190
• 4 Haffner SM, D’Agostino R, Saad MF, Rewers M, Mykkanen L, Selby J, Howard G, Savage PJ, Hamman RF, Wagenknecht LE. Increased insulin resistance and insulin secretion in nondiabetic African-Americans and Hispanics compared with non-Hispanic whites. The Insulin Resistance Atherosclerosis Study.  Diabetes. 1996;  45 742-748
• 5 Carnethon MR, Palaniappan LP, Burchfiel CM, Brancati FL, Fortmann SP. Serum insulin, obesity, and the incidence of type 2 diabetes in black and white adults: the atherosclerosis risk in communities study: 1987–1998.  Diabetes Care. 2002;  25 1358-1364
• 6 Novoa FJ, Boronat M, Saavedra P, Diaz-Cremades JM, Varillas VF, La Roche F, Alberiche MP, Carrillo A. Differences in cardiovascular risk factors, insulin resistance, and insulin secretion in individuals with normal glucose tolerance and in subjects with impaired glucose regulation: the Telde Study.  Diabetes Care. 2005;  28 2388-2393
• 7 Bassuk SS, Manson JE. Epidemiological evidence for the role of physical activity in reducing risk of type 2 diabetes and cardiovascular disease.  J Appl Physiol. 2005;  99 1193-1204
• 8 Palaniappan LP, Carnethon MR, Fortmann SP. Heterogeneity in the relationship between ethnicity, BMI, and fasting insulin.  Diabetes Care. 2002;  25 1351-1357
• 9 Uwaifo GI, Nguyen TT, Keil MF, Russell DL, Nicholson JC, Bonat SH, McDuffie JR, Yanovski JA. Differences in insulin secretion and sensitivity of Caucasian and African American prepubertal children.  J Pediatr. 2002;  140 673-680
• 10 Lovejoy JC, de la Bretonne JA, Klemperer M, Tulley R. Abdominal fat distribution and metabolic risk factors: effects of race.  Metabolism. 1996;  45 1119-1124
• 11 Albu JB, Kovera AJ, Allen L, Wainwright M, Berk E, Raja-Khan N, Janumala I, Burkey B, Heshka S, Gallagher D. Independent association of insulin resistance with larger amounts of intermuscular adipose tissue and a greater acute insulin response to glucose in African American than in white nondiabetic women.  Am J Clin Nutr. 2005;  82 1210-1217
• 12 Marcus MA, Murphy L, Pi-Sunyer FX, Albu JB. Insulin sensitivity and serum triglyceride level in obese white and black women: relationship to visceral and truncal subcutaneous fat.  Metabolism. 1999;  48 194-199
• 13 Bjorntorp P, Holm G, Rosmond R. Hypothalamic arousal, insulin resistance and Type 2 diabetes mellitus.  Diabet Med. 1999;  16 373-383
• 14 Vicennati V, Pasquali R. Abnormalities of the hypothalamic-pituitary-adrenal axis in nondepressed women with abdominal obesity and relations with insulin resistance: evidence for a central and a peripheral alteration.  J Clin Endocrinol Metab. 2000;  85 4093-4098
• 15 Binnert C, Ruchat S, Nicod N, Tappy L. Dexamethasone-induced insulin resistance shows no gender difference in healthy humans.  Diabetes Metab. 2004;  30 321-326
• 16 Nicod N, Giusti V, Besse C, Tappy L. Metabolic adaptations to dexamethasone-induced insulin resistance in healthy volunteers.  Obes Res. 2003;  11 625-631
• 17 Fajans SS, Conn JW. An approach to the prediction of diabetes mellitus by modification of the glucose tolerance test with cortisone.  Diabetes. 1954;  3 296-302 discussion, 302–294
• 18 Henriksen JE, Alford F, Ward GM, Beck-Nielsen H. Risk and mechanism of dexamethasone-induced deterioration of glucose tolerance in non-diabetic first-degree relatives of NIDDM patients.  Diabetologia. 1997;  40 1439-1448
• 19 Ehrmann DE, Breda E, Corcoran MC, Cavaghan MK, Imperial J, Toffolo G, Cobelli C, Polonsky KS. Impaired beta-cell compensation to dexamethasone-induced hyperglycemia in women with polycystic ovary syndrome.  Am J Physiol Endocrinol Metab. 2004;  287 E241-E246
• 20 Besse C, Nicod N, Tappy L. Changes in insulin secretion and glucose metabolism induced by dexamethasone in lean and obese females.  Obes Res. 2005;  13 306-311
• 21 Darmon P, Dadoun F, Boullu-Ciocca S, Grino M, Alessi MC, Dutour A. Insulin resistance induced by hydrocortisone is increased in patients with abdominal obesity.  Am J Physiol Endocrinol Metab. 2006;  291 E995-E1002
• 22 Lyssenko V, Almgren P, Anevski D, Perfekt R, Lahti K, Nissen M, Isomaa B, Forsen B, Homstrom N, Saloranta C, Taskinen MR, Groop L, Tuomi L. Predictors of and longitudinal changes in insulin sensitivity and secretion preceding onset of type 2 diabetes.  Diabetes. 2005;  54 166-174
• 23 Franciosi M, De Berardis G, Rossi MC, Sacco M, Belfiglio M, Pellegrini F, Tognoni G, Valentini M, Nicolucci A. Use of the diabetes risk score for opportunistic screening of undiagnosed diabetes and impaired glucose tolerance: the IGLOO (Impaired Glucose Tolerance and Long-Term Outcomes Observational) study.  Diabetes Care. 2005;  28 1187-1194
• 24 Baan CA, Ruige JB, Stolk RP, Witteman JC, Dekker JM, Heine RJ, Feskens EJ. Performance of a predictive model to identify undiagnosed diabetes in a health care setting.  Diabetes Care. 1999;  22 213-219
• 25 Ward AM, Fall CH, Stein CE, Kumaran K, Veena SR, Wood PJ, Syddall HE, Phillips DI. Cortisol and the metabolic syndrome in South Asians.  Clin Endocrinol (Oxf). 2003;  58 500-505
• 26 Paul K, Boutain D, Agnew K, Thomas J, Hitti J. The relationship between racial identity, income, stress and C-reactive protein among parous women: implications for preterm birth disparity research.  J Natl Med Assoc. 2008;  100 540-546
• 27 Fiscella K, Franks P. Does psychological distress contribute to racial and socioeconomic disparities in mortality?.  Soc Sci Med. 1997;  45 1805-1809
• 28 Schulz A, Israel B, Williams D, Parker E, Becker A, James S. Social inequalities, stressors and self reported health status among African American and white women in the Detroit metropolitan area.  Soc Sci Med. 2000;  51 1639-1653

Correspondence