Plasma adiponectin levels in high risk African-Americans with normal glucose tolerance, impaired glucose tolerance, and type 2 diabetes.
OBJECTIVE
We studied plasma adiponectin, insulin sensitivity, and insulin secretion before and after oral glucose challenge in normal glucose tolerant, impaired glucose tolerant, and type 2 diabetic first degree relatives of African-American patients with type 2 diabetes.


METHODS
We studied 19 subjects with normal glucose tolerance (NGT), 8 with impaired glucose tolerance (IGT), and 14 with type 2 diabetes. Serum glucose, insulin, C-peptide, and plasma adiponectin levels were measured before and 2 hours after oral glucose tolerance test. Homeostasis model assessment-insulin resistance index (HOMA-IR) and HOMA-beta cell function were calculated in each subject using HOMA. We empirically defined insulin sensitivity as HOMA-IR<2.68 and insulin resistance as HOMA-IR>2.68.


RESULTS
Subjects with IGT and type 2 diabetes were more insulin resistant (as assessed by HOMA-IR) when compared with NGT subjects. Mean plasma fasting adiponectin levels were significantly lower in the type 2 diabetes group when compared with NGT and IGT groups. Plasma adiponectin levels were 2-fold greater (11.09+/-4.98 vs. 6.42+/-3.3811 microg/mL) in insulin-sensitive (HOMA-IR, 1.74+/-0.65) than in insulin-resistant (HOMA-IR, 5.12+/-2.14) NGT subjects. Mean plasma adiponectin levels were significantly lower in the glucose tolerant, insulin-resistant subjects than in the insulin sensitive NGT subjects and were comparable with those of the patients with newly diagnosed type 2 diabetes. We found significant inverse relationships of adiponectin with HOMA-IR (r=-0.502, p=0.046) and with HOMA-beta cell function (r=-0.498, p=0.042) but not with the percentage body fat (r=-0.368, p=0.063), serum glucose, BMI, age, and glycosylated hemoglobin A1C (%A1C).


CONCLUSIONS
In summary, we found that plasma adiponectin levels were significantly lower in insulin-resistant, non-diabetic first degree relatives of African-American patients with type 2 diabetes and in those with newly diagnosed type 2 diabetes. We conclude that a decreased plasma adiponectin and insulin resistance coexist in a genetically prone subset of first degree African-American relatives before development of IGT and type 2 diabetes.
Osei
Kwame
K
Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, 491 McCampbell Hall, The Ohio State University College of Medicine and Public Health, Columbus OH 43210, USA. osei-1@medctr.osu.edu
Gaillard
Trudy
T
Schuster
Dara
D
D052242:Adiponectin; D044383:Black People; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure / Q000502:physiology; D002096:C-Peptide / Q000378:metabolism; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000235:genetics / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period / Q000502:physiology; D012307:Risk Factors; D018709:Statistics, Nonparametric; D001741:Black or African American
D052242:Adiponectin; D001786:Blood Glucose; D002096:C-Peptide; D006442:Glycated Hemoglobin; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins