Browsing by Author "Osei, K."
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Item Assessing the Explanatory Power of Book to Market Value of Equity Ratio (BTM) on Stock Returns on Ghana Stock Exchange (GSE)(University of Ghana, 2012-06) Brobbey, F.O.; Aboagye, A.Q.Q.; Osei, K.The objective of this research was to assess the explanatory power of Book-To-Market value of equity ratio (BTM) and firm size on portfolio returns in Ghana. This study also sought to compare the strength of BTM to size in explaining returns. The last objective was to measure the efficiency of Fama and French (1992) Three-Factor Model on the Ghana Stock Exchange (GSE) over the period January 1997 to December 2009 and to compare the Three-Factor Model to the Capital Asset Pricing Model (CAPM). The sample includes only non-financial firms that traded on the Ghana Stock Exchange over the test period. The sample size increased from eleven (11) non-financial firms in 1997 to twenty-one (21) non- financial firms in 2009. Each year, six Size-BTM sorted portfolios are formed namely; Big-High (BH) portfolio which consist of stocks with big size and high BTM ratio, Big-Medium (BM) portfolio which contains stocks with big size but medium BTM ratio , Big-Low(BL) portfolio which consist of stocks with big size and Low BTM ratio, Small-High (SH) portfolio which contains stocks with small size and high BTM ratio, Small- Medium (SM) portfolio contains small size and medium BTM ration whilst Small-Low (SL) portfolio contains stocks with small size but low BTM ratio. This research found out that, CAPM alone could not predict portfolio returns and that by adding the two other factors, namely the size effect and the book-to-market ratio effect, to the CAPM to derive the Fama and French (1992) Three- Factor Model improves the efficiency of the explanation. It was therefore concluded that The Fama and French Three - Factor Model consisting of Beta, BTM and firm size could explain risk in portfolio return better than the beta alone as contended by the traditional CAPM. This study also identified that BTM effect was stronger on the Ghanaian market than the size effect as identified by Fama and French (1992) on the US market.Item Barriers and Enablers to Uptake of HIV Prevention Services among Men Who-Have-Sex with Men (MSMs) in the Accra Metropolitan Area(University Of Ghana, 2019-07) Osei, K.Introduction: Populations considered as having a high risk to HIV infection are known as key populations (KPs). There has been substantial funding for HIV programmes for Men who-have-sex with Men (MSM), however, the prevalence of MSM in Ghana increased from 17.1% in 2011 to 18% in 2017 which is higher than the HIV prevalence among the general population which is 1.67%. This is also coupled with low uptake of HIV prevention services. It is therefore important to explore what could be enabling and hindering their uptake of available HIV prevention services to guide future policies and plans targeting them. Objective: To explore predisposing factors that influence uptake of HIV prevention services among MSM, to examine enabling factors that influence uptake of HIV prevention services among MSM and identify need factors that influence uptake of HIV prevention services among MSM in the Accra Metropolitan Area. Methods: The study adopted an exploratory qualitative research approach and study population consisted of 15 MSM peer educators directly involved in HIV prevention services and a management staff of Centre for Popular Education and Human Rights Ghana. Results: The study showed the importance of peer educators in supporting uptake of HIV prevention services in the community. However, some factors such as low knowledge about prevention services, unfriendly legal environment and negative attitudes of community members affected the uptake of HIV prevention services among MSM. Conclusion: The study results identified some barriers to uptake of HIV prevention services by MSM as low level of education of MSM, income levels of MSM and negative attitudes of health workers. Some enablers included the presence of peer educators, and formation of support groups. It is important that these factors identified are urgently addressed to improve uptake of HIV prevention services among MSM. Keywords: HIV, testing, uptake, prevention, peer educators, barriers, enablers, MSM, AccraItem Central bank independence, elections and fiscal policy in Africa: Examining the moderating role of political institutions(International Journal of Emerging Markets, 2019-12-02) Agoba, A.M.; Abor, J.Y.; Osei, K.; Sa-Aadu, J.; Amoah, B.; Dzeha, G.C.O.Purpose – The purpose of this paper is to primarily investigate the ability of independent central banks (central bank independence (CBI)) to improve fiscal performances in Africa, accounting for election years, and also to examine whether the effectiveness of CBI in improving fiscal performance is enhanced by higher political institutional quality. Design/methodology/approach – Using recent CBI data from Garriga (2016) on 48 African countries, 90 other developing countries and 40 developed countries over the period 1970–2012, the authors apply a two stage system GMM with Windmeijer (2005) small sample robust correction estimator to examine the impact of CBI and elections on fiscal policy in Africa, other developing countries and developed countries. Findings – The authors provide evidence that unlike in other developing countries and developed countries, CBI does not significantly improve fiscal performance in Africa. However, the effectiveness of CBI in improving fiscal performance in Africa is enhanced by higher levels of institutional quality. Although elections directly worsen fiscal performance in Africa, institutional quality enhances CBI’s effect on improving fiscal performance in election years across Africa, other developing countries and developed countries. Practical implications – The findings of the study are significant as they provide insight into the benefits of having strong institutions to complement independent central banks in order to control fiscal indiscipline in election years. Originality/value – The study is the first among the studies of CBI-fiscal policy nexus, to measure fiscal policy using net central bank claims on government as a percentage of GDP. In addition to the use of fiscal balance, this study also uses cyclically adjusted fiscal balance as a measure of fiscal policy. This is a critical channel through which independent central banks can constrain governItem Connectedness Across Commodities, Stocks, Exchange Rates And Bonds Markets In Africa: The Covid-19 Pandemic Case(International Journal of Emerging Markets, 2023) Boakye, R.O.; Mensah, L.; Osei, K.; et al.Purpose: The study measures the total systemic risks and connectedness across commodities, stocks, exchange rates and bond markets in Africa during the Covid-19 pandemic. Design, methodology, and approach: The study uses Diebold-Yilmaz spillover and connectedness measures in a generalized VAR framework. The author calculates the net transmitters or receivers of shocks between two assets and visualizes their strength using a network analysis tool. Findings: The study found low systemic risks across all assets and countries. However, we found higher systemic risks in the forex market than in the stock and bond markets, and in South Africa than in other countries. The dynamic analysis found time-varying connectedness return shocks, which increased during the peak periods of the first and second waves of the pandemic. We found both gold and oil as net receivers of shocks. Overall, over half of all assets were net receivers, and others were net transmitters of return shocks. The network's connectedness plot shows high net pairwise connectedness from Morocco to South African stock market. Practical implications: The study has implications for policymakers to develop the capacities of local investors and markets to limit portfolio outflows during a crisis. Originality/value: Previous studies have analyzed spillovers across asset classes in a single country or a single asset across countries. This paper contributes to the literature on network connectedness across assets and countries.Item Does financial inclusion Spur Financial Development in Africa?(University of Ghana, 2014-07) Abor, J.; Osei, K.; Mensah, LordThis study assessed the impact of financial inclusion on financial development in Africa. Using cross-section data covering forty-two African countries, the study uses regression analysis, to establish how the banking sector development is affected by financial inclusion. In this study, financial development used as the dependent variable is proxied by the ratios of money supply, bank credit and private credit to Gross Domestic Product. The independent variables include financial inclusion measured with two variables (accounts used to receive wages, and individual formal account) obtained by carrying out principal component analysis of fourteen (14) measures of financial inclusion. The other independent variables used are inflation, financial openness, a measure of institutional quality and natural resource endowment of the country. The empirical result revealed that higher levels of financial inclusion lead to financial development in the banking sector. In addition, institutional quality were found to have a positive effect on financial development whiles inflation and natural resource rents were found to have negative effects on financial development. Based on the findings of this study, it is recommended that the government, policy makers and the banks put in place delebrate measures to provide unrestricted access to financial services to the people. Also, whilst promoting the financial inclusion phenomenon, there is the need to maintain strong institutions and at the same time prudent measures to mitigate economic instability.Item Facilities and resources for diabetes care at regional health facilities in southern Ghana(Diabetes Research and Clinical Practice, 1998-11) Amoah, A.G.; Owusu, S.K.; Saunders, J.T.; Fang, W.L.; Asare, H.A.; Pastors, J.G.; Sanborn, C.; Barrett, E.J.; Woode, M.K.A.; Osei, K.In the fall of 1995, each of the five provincial hospitals in southern Ghana was visited and facilities and resources for diabetes care assessed. In addition, health facilities and standards of care questionnaires were completed. Only Korle Bu Teaching Hospital run a diabetes clinic and had diabetologists. Only two facilities had an eye specialist or trained dietician. None of the five facilities had a trained diabetes educator or chiropodist. Except for sphygmomanometers, basic equipment for clinical care were lacking. Basic biochemistry tests were available at all facilities. Creatinine clearance and 24-h urine protein, glycated haemoglobin, fasting triglyceride, total cholesterol and HDL cholesterol were available at only one centre. None of the facilities measured C-peptide, islet cell antibody and urine microalbumin. None of the facilities had chronic haemodialysis service. Insulin supply was erratic at two institutions. Three regions had active diabetes associations. The facilities and system of diabetes care in southern Ghana revealed in this study are far from satisfactory. Training of health care personnel in diabetes management and education may enhance diabetes care despite the existing constraints. Furthermore, the development of international and regional gradelines for facilities and resources may facilitate implementation of international resolutions and clinical practice guidelines.Item FDI and Economic Activity in Africa: The Role of Local Financial Markets(2012) Adjasi, C.; Abor, J.; Osei, K.; Nyavor-Foli, E.This article examines the role local financial markets play in the link between foreign direct investment (FDI) and economic activity. The article uses panel data methods on 32 African countries over the period 1997 to 2008. Our results show that FDI only has a significant effect on economic activity when interacted with financial market variables, namely, private-sector credit and savings. The results of this study imply that FDI is more productive in the presence of well-functioning local financial markets. African governments must therefore pay particular attention to developing further local financial markets to ensure full economic benefits of FDI inflows. © 2012 Wiley Periodicals, Inc.Item Financing Cost and Private Investment in Ghana(University of Ghana, 2010-06) Ofosu-Mensah Ababio, J.; Osei, K.; Kumankuma, S.; University of Ghana, College of Humanities, Business School, Department of Banking and FinanceThis study has investigated empirically the effect o f Financing Cost on Private Investment in Ghana, over the period 1970 - 2008. To this end, the variables used were classified as Cost factors and Non Cost factors o f private investment, using the latter as control variables. The private investment function derived is a variant o f the flexible accelerator principle designed to account for the objective o f the study. It employed the Augmented D ickey-Fuller (ADF) test to address the problem o f unit root faced in time series analysis. The long run estimate o f the private investment function for Ghana was estimated using the Johansen co-integration technique. The Error Correction model was used to determine the short-run dynamics o f the variables used in the model. The study found that all the cost factors (interest rate, inflation rate, exchange rate and budget deficit) had negative and statistically significant impact on private investment in the long run. On the other hand, in the long run. the non cost factors (credit to the private sector, real GDP and public investment) impacted positively on private investment but external debt had adverse effect. The results also found that with the exception o f the stock market variable, all the variables used co-integrated with private investment. The study further revealed that not all the variables used were significant in the long run, since variables such as public investment and external debt had the expected signs but were not significant. This study provided direct evidence that high cost o f financing is associated with low private sector participation in investment activities in Ghana. Accordingly, the study recommended among others that long term policies should be directed towards cost control and macroeconomic stabilization in order to boost private investment in Ghana.Item Insulin resistance, beta cell function and cardiovascular risk factors in Ghanaians with varying degrees of glucose tolerance(Ethnicity & Disease, 2002-09) Amoah, A.G.; Schuster, D.P.; Gaillard, T.; Osei, K.Objective: Type 2 diabetes is characterized by beta cell dysfunction and insulin resistance (IR). The disease is associated with high rates of cardiovascular mortality and morbidity. Recently, the American Diabetes Association Expert Committee recommended the measurement of fasting glucose as a tool for screening and diagnosing diabetes, in order to identify patients with a mild form of the disease as well as to enhance the detection of undiagnosed type 2 diabetes. The significance of these criteria with respect to cardiovascular risk factors in native Ghanaians is unknown. The objectives of the present study were to examine the cardiovascular risk factors in a sample of native Ghanaians with varying degrees of glucose intolerance as defined by fasting glucose levels as specified by the ADA criteria. Research and Methods: The population consisted of 200 indigenous Ghanaian subjects, age range 25-74 years, residing in the Accra metropolitan areas. Subjects were categorized using the fasting plasma glucose (FPG) alone as normal fasting glucose (NFG, FPG<110mg/dL), impaired fasting glucose (IFG, 110126mg/dL). Anthropometric parameters (blood pressure, waist circumference and waist-hip circumference ratios) were measured in each subject. Levels of serum glucose, c-peptides and insulin were measured at baseline and after 2 hours of oral glucose challenge. Insulin resistance (HOMA-IR) and beta cell function (HOMA-%B) were assessed by homeostasis model assessment (HOMA). Levels of fasting serum cholesterol, high-density lipoprotein cholesterol (HDL-C), cholesterol, and triglycerides were measured in each subject. Results: There were 181 subjects in the NFG category, 11 in the IFG category, and 8 newly diagnosed type 2 diabetic subjects. The mean age, BMI, waist circumference (WC), and WHR did not differ between the 3 groups. The mean fasting glucose and the corresponding 2-hour glucose levels rose with the worsening of glucose tolerance. Similarly, the means for serum fasting, post-challenge serum insulin, and c-peptide levels were significantly greater in the IFG and DM groups. Fasting serum cholesterol and high density lipoproteins did not differ statistically between the 3 groups, However, the means for serum triglycerides were greater in the IFG and DM groups when compared to the NFG group. The insulin resistance (IR) as assessed by HOMA was 2X and 4X greater in the Conclusions: We have characterized the metabolic and anthropometric risk factors for CVD in native Ghanaians with varying degrees of glucose tolerance, as defined by the ADA criteria. We found that both IFG and DM were associated with beta cell dysfunction, insulin resistance, and elevated serum triglycerides. However, the well established cardiovascular risk factors, such as body mass index, body fat distribution, and blood pressure did not track with the increasing glucose intolerance in the native Ghanaians. We conclude that the Ghanaian patients with IFG and type 2 diabetes were non-obese and exhibited severe beta cell dysfunction, insulin resistance, and elevated triglycerides, but none of the other conventional risk factors, at the time of diagnosis. Future research should focus on the sequential changes in risk factors during development of cardiovascular diseases in native Ghanaians with varying degrees of glucose tolerance.Item Insulin sensitivity and cardiovascular risk factors in hypertensive and normotensive native ghanaians(Diabetologia, 2003-07-01) Amoah, A.G.; Schuster, D.P.; Gaillard, T.; Osei, K.Aims/Hypothesis. The objective of this study was to examine the relationships among insulin and insulin sensitivity and risk factors for cardiovascular diseases in native Ghanaians with and without hypertension. Methods. We measured the anthropometric parameters, systolic and diastolic blood pressure, fasting serum triglycerides, cholesterol and high-density lipoprotein cholesterol and fasting and stimulated glucose, insulin and C-peptide of 200 Ghanaian subjects, who were between 25 to 74 years of age, and residing in the Accra Metropolitan area. Serum glucose, C-peptide and insulin concentrations were measured at baseline (fasting) and also 2 h after 75 gm oral glucose drink. Homeostasis model assessment was used to measure insulin resistance. Hypertension was defined as a blood pressure higher than 140/90 mmHg. Results. There were 53 subjects with hypertension (HBP) and 147 subjects with normal blood pressure (NBP). The mean BMI, waist circumference and waist-to-hip circumference ratio for HBP and NBP subjects were 27.4±0.8, 24.8±0.4 kg/m 2; 89.8±11.7, 81.1±0.9 cm; and 0.87±0.08, 0.82±0.08 respectively, (p<0.05). The fasting and 2-h plasma glucose concentrations in HBP and NBP subjects were 5.5±0.2, 7.2±0.3 mmol/1 and 5.2±01, 6.8±0.2 mmol/l respectively (p>0.05). The corresponding fasting and 2-h insulin concentrations were 10.0±0.7, 8.0±0.4 uU/ml and 47.3±3.7, 37.3±2.5 uU/ml respectively (p<0.05). The insulin resistance index (HOMA-IR) in the HBP and the NBP groups were 2.49±0.2 and 1.95±0.13 (p<0.05). The two groups had similar fasting and stimulated C-peptide, lipids and HDL concentrations. Correlations were found between blood pressure and the concentrations of lipids, HDL, fasting and stimulated insulin and C-peptide, and between fasting insulin and HOMA-IR with lipids and HDL concentrations. On multiple regression analysis, fasting insulin and HOMA-IR did not influence blood pressure variations significantly. Conclusions/interpretation. We found clustering of hyperinsulinaemia, insulin resistance and truncal obesity in hypertensive Ghanaian subjects but dissociation between insulin resistance, hypertension and atherogenic lipid and lipoprotein profile.Item Minimal model analyses of beta cell secretion, insulin sensitivity and glucose effectiveness in glucose tolerant, non-diabetic first-degree relatives of Ghanaian patients with type 2 diabetes and healthy control subjects(Ethnicity & Disease, 2001-03) Amoah, A.G.; Owusu, S.K.; Ayittey, O.M.; Schuster, D.P.; Osei, K.Objective: We have examined the importance of positive family history of type 2 diabetes on serum glucose, insulin sensitivity, and beta cell secretion in native West Africans (Ghanaians) who reside in their native country. Research and Methods: We evaluated the beta cell secretion, insulin secretion, insulin sensitivity (Si), and glucose effectiveness (Sg) in 42 healthy non-diabetic first-degree relatives of Ghanaian patients with type 2 diabetes (26 females and 16 males) and in 22 healthy control subjects without a family history of type 2 diabetes (12 females and 10 males) living in Accra, Ghana, West Africa. A standard oral glucose tolerance test (OGTT) and a frequently sampled intravenous glucose tolerance (FSIGT) test were performed in each subject. Si and Sg were measured using Bergman's minimal model method. Results: During oral glucose challenge, fasting and postprandial serum glucose levels were not significantly different between the relatives and healthy controls. Mean serum insulin and c-peptide responses after oral glucose tolerance test at t = 60, 90 and 120 minutes (P<.05) were significantly greater in the relatives than in the healthy controls. During the FSIGT, the mean serum glucose responses did not differ. Mean total and acute first and second phases of serum insulin and c-peptide responses were greater in the relatives than in the healthy controls. We found that the Si tended to be lower in the relatives than in the controls, but the mean difference did not vary significantly between the two groups. In addition, the glucose effectiveness at basal insulin level (Sg) was not significantly different in the relatives and healthy controls. Conclusions: The present study demonstrates that hyperinsulinemia and a tendency to lower insulin sensitivity (insulin resistance), but not altered glucose effectiveness, are found in healthy non-diabetic, first-degree relatives of Ghanaian patients with type 2 diabetes as compared to healthy subjects living in their native country. We conclude that genetic factors could play a significant role in the development of type 2 diabetes in indigenous Ghanaians residing in their native country.Item Pathogenesis of type 1 and type 2 diabetes mellitus in sub-Saharan Africa: implications for transitional populations(Journal of Cardiovascular Risk, 2003-04) Osei, K.; Schuster, D.P.; Amoah, A.G.; Owusu, S.K.The increasing prevalence and incidence of diabetes and its long-term complications in sub-Saharan Africa (SSA) could have devastating human and economic toll if the trends remain unabated in the future. Approximately 90% or majority of patients with diabetes belongs to the adult onset, type 2 diabetes category while 10% have type 1 diabetes in SSA. However, because of the paucity of metabolic and clinical data, a clear understanding of the natural history of both diseases and the classification of diabetes subtypes has been hampered. Nevertheless, we have attempted to provide a concise review of the pathophysiology of both type I and type 2 diabetes as well as phenotypic and clinical variations in patients residing in SSA. The limited metabolic data, (albeit increasing), from high-risk and diabetic individuals in the SSA, have contributed significantly to the understanding of the pathogenetic mechanisms of diabetes and the variations in the presentation of the disease. Sub-Saharan African patients with type I diabetes have essentially absolute insulin deficiency. In addition, patients with type 2 diabetes in SSA region also manifest severe insulin deficiency with varying degrees of insulin resistance. Although the exact genetic markers of both diseases are unknown, we believe studies in patients of SSA origin who reside in diverse geographic environments (African diaspora) could potentially contribute to our understanding of the genetic and environmental mediators of both diseases. However, many intrinsic, individual and societal obstacles such as poor education and illiteracy, low socio-economic status and lack of access to health care make uncertain the translation of diabetes research in SSA. In this regard, effective management and/or prevention of diabetes in SSA individuals should adopt multidisciplinary approaches. Finally, innovative health care delivery and educational models will be needed to manage diabetes and its long-term complications in SSA.Item Pathogenic mechanism of type 2 diabetes in Ghanaians--the importance of beta cell secretion, insulin sensitivity and glucose effectiveness(South African Medical Journal, 2002) Amoah, A.G.; Owusu, S.K.; Schuster, D.P.; Osei, K.Objective. To assess insulin sensitivity and beta cell secretion in indigenous Ghanaian subjects with a spectrum of glucose intolerance. Research and methods. We evaluated beta cell secretion, insulin sensitivity (Si) and glucose effectiveness (Sg) in three groups: group 1, 15 healthy control subjects without family history of type 2 diabetes; group 2, 11 healthy non-diabetic first-degree relatives of Ghanaian patients with type 2 diabetes; and group 3, 10 patients with type 2 diabetes living in Accra, Ghana, West Africa. A standard oral glucose tolerance test (OGTT) and frequently sampled intravenous glucose tolerance (FSIGT) test were performed for each subject. Si and Sg were measured using Bergman's minimal model method. Results. The mean body mass index (BMI) and lean body mass were not different among the three groups. However, the waist-to-hip circumference ratio, total body fat as well as triceps and biceps skinfolds were significantly greater in group 3 (diabetic patients) than in group 2 (relatives) and group 1 (healthy controls). Mean fasting and postprandial serum glucose levels were not significantly different between the relatives and healthy controls during oral glucose challenge. The mean fasting and postprandial serum glucose levels were significantly higher in the group 3 diabetic patients than in the non-diabetic groups. Mean fasting serum insulin and C-peptide levels tended to be higher in group 3 than in groups 1 and 2. However, mean serum insulin and C-peptide responses after oral glucose load were significantly greater in group 2 than in the group 1 healthy controls. The insulin responses in the two non-diabetic groups after oral glucose challenge were significantly greater than in the diabetic patients. During the FSIGT, the mean serum glucose responses were similar in the two non-diabetic groups (groups 1 and 2). The serum glucose responses were significantly greater in group 3 than in the non-diabetic groups. Mean total and acute first and second phases of insulin and C-peptide responses were greater in group 2 than group 1. However, acute phases of insulin secretion were severely blunted in group 3 when compared with groups 1 and 2 during FSIGT in our Ghanaians. We found that the mean Si was slightly lower in group 2 (1.72 ± 0.32) than in the healthy controls in group 1 (1.9 ± 0.55, P = NS). Mean Si was remarkably lower in the diabetic patients in group 3 (1.30 ± 0.35 x 10-4/min (μU/ml)) when compared with the relatives and healthy controls, but the differences were not statistically significant. Mean glucose effectiveness at basal insulin level (Sg) was not significantly different among the relatives in group 2 (2.38 ± 0.50), the healthy controls in group 1 (2.66 ± 0.38) and the diabetic patients in group 3 (2.27 ± 0.49 x 10-2/min). Conclusions. We conclude that (i) the pathogenetic mechanisms of type 2 diabetes in indigenous Ghanaians are characterised by severe beta cell dysfunction and moderate reduction in Si. Although the healthy relatives manifest insulin resistance with compensatory hyperinsulinaemia, our study suggests that the conversion of such subjects to type 2 diabetes is determined by deterioration in beta cell function and perhaps Si but not tissue Sg in Ghanaians. Prospective studies are needed to examine the sequential changes that lead to the development of type 2 diabetes in indigenous Ghanaians.Item Race and ethnicity determine serum insulin and C-peptide concentrations and hepatic insulin extraction and insulin clearance: comparative studies of three populations of West African ancestry and white Americans(Metabolism, 1997) Osei, K.; Schuster, D.P.; Owusu, S.K.; Amoah, A.G.We examined the importance of ethnicity in terms of β-cell secretion and hepatic insulin extraction (HIE) and insulin clearance (IC) to peripheral insulin levels before and after stimulation in three populations of West African ancestry, namely African-Americans, Ghanaian immigrants, and native Ghanaians living in diverse environments, and white Americans. Following 10 to 12 hours of overnight fasting, each subject ingested a 75-g oral glucose load. Blood samples for determination of serum glucose, insulin, and C- peptide were obtained at baseline and after the oral glucose load at 30- minute intervals for 240 minutes. Basal HIE and IC were calculated as the molar ratios of C-peptide and insulin concentrations at basal steady state, and postprandial values as molar ratios of the incremental integrated C- peptide and insulin areas. Clinical characteristics of the patients were not significantly different among the four groups. During the fasting and postprandial state, serum glucose levels were not significantly different among the four groups. Surprisingly, the mean fasting insulin concentration was significantly greater in native Ghanaians (21.19 ± 0.93 μU/mL, P < .05) than in African-Americans (11.90 ± 1.02 μU/ML), Ghanaian immigrants (8.14 ± 0.96 μU/mL), and white Americans (7.03 ± 0.78 μU/mL). Following the oral glucose load, the mean serum peak and incremental integrated areas of insulin were significantly (P < .05) greater in native Ghanaians, African- Americans, and Ghanaian immigrants compared with white Americans. In contrast, there were no significant differences in postprandial serum insulin responses among the three groups of West African ancestry, irrespective of country of origin or residence. Despite the higher insulin concentrations in blacks of West African ancestry compared with whites, the corresponding basal and postprandial serum C-peptide levels were not significantly different among the four groups. Mean basal and postprandial HIE and IC were significantly (P < .05 to .01) reduced (25% to 52%) in the three populations of West African ancestry compared with the white Americans, but these values were not significantly different among the West African descendants. When comparing metabolic responses in obese (body mass index [BMI] > 27 kg/m2) and non-obese (BMI < 27 kg/m2) native Ghanaians, we found no significant differences in fasting insulin, C-peptide, and basal HIE or IC. Also, there were no significant relations between fasting and postprandial serum insulin, obesity indices, and HIE and IC in any of the groups. In summary, our study demonstrates that glucose-tolerant native Ghanaians, Ghanaian immigrants, and African-Americans of West African ancestry manifest hyperinsulinemia and a decreased HIE and IC compared with white Americans. We conclude that race and ethnicity may be the major determinants of the mechanism(s) of β-cell secretion, insulin action, and peripheral insulin levels and HIE or IC in humans. We speculate that the lower HIE and IC in blacks of West African descent appears to be a highly conserved metabolic trait irrespective of the country of residence.