Amoah Albert G B, Schuster Dara P, Gaillard Trudy, Osei Kwame
Diabetes Research Laboratory, Department of Medicine and Therapeutics, University of Ghana Medical School, Accra, Ghana.
Ethn Dis. 2002 Fall;12(4):S3-10-7.
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.
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 < 110 mg/ dL), impaired fasting glucose (IFG, 11 < FPG 126 mg/dL), and diabetic (DM, FPG > 126 mg/ 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.
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 IFG (3.76) and DM (6.12) groups when compared with the NFG (1.82, P < .05).
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.
2型糖尿病的特征是β细胞功能障碍和胰岛素抵抗（IR）。该疾病与心血管疾病的高死亡率和高发病率相关。最近，美国糖尿病协会专家委员会建议将空腹血糖测量作为筛查和诊断糖尿病的工具，以便识别病情较轻的患者，并加强对未确诊的2型糖尿病的检测。这些标准对于加纳本土人心血管危险因素的意义尚不清楚。本研究的目的是根据美国糖尿病协会（ADA）标准规定的空腹血糖水平，检查不同程度糖耐量异常的加纳本土人样本中的心血管危险因素。
研究人群包括200名年龄在25 - 74岁之间、居住在阿克拉大都市区的加纳本土受试者。仅使用空腹血糖（FPG）将受试者分为正常空腹血糖（NFG，FPG < 110 mg/dL）、空腹血糖受损（IFG，110≤FPG<126 mg/dL）和糖尿病（DM，FPG > 126 mg/dL）。测量每个受试者的人体测量参数（血压、腰围和腰臀比）。在基线和口服葡萄糖耐量试验2小时后测量血清葡萄糖、C肽和胰岛素水平。通过稳态模型评估（HOMA）评估胰岛素抵抗（HOMA-IR）和β细胞功能（HOMA-%B）。测量每个受试者的空腹血清胆固醇、高密度脂蛋白胆固醇（HDL-C）、胆固醇和甘油三酯水平。
NFG组有181名受试者，IFG组有11名受试者，8名新诊断的2型糖尿病受试者。三组之间的平均年龄、体重指数、腰围（WC）和腰臀比无差异。随着糖耐量恶化，平均空腹血糖和相应的2小时血糖水平升高。同样，IFG组和DM组的空腹血清、口服葡萄糖耐量试验后血清胰岛素和C肽水平平均值显著更高。三组之间空腹血清胆固醇和高密度脂蛋白无统计学差异，然而，与NFG组相比，IFG组和DM组的血清甘油三酯平均值更高。与NFG组（1.82，P < 0.05）相比，通过HOMA评估的IFG组（3.76）和DM组（6.12）的胰岛素抵抗（IR）分别高2倍和4倍。
我们已经描述了根据ADA标准定义的不同程度糖耐量异常的加纳本土人心血管疾病的代谢和人体测量危险因素。我们发现IFG和DM均与β细胞功能障碍、胰岛素抵抗和血清甘油三酯升高有关。然而，加纳本土人中，诸如体重指数、体脂分布和血压等公认的心血管危险因素并未随着糖耐量异常的增加而变化。我们得出结论，加纳IFG和2型糖尿病患者在诊断时并非肥胖，而是表现出严重的β细胞功能障碍、胰岛素抵抗和甘油三酯升高，但无其他传统危险因素。未来的研究应关注不同程度糖耐量异常的加纳本土人心血管疾病发展过程中危险因素的顺序变化。
