title: Elevated A1C is associated with impaired early-phase insulin secretion rather than insulin resistance in Koreans at high risk for developing diabetes.
abstract: The purpose of this study is to examine the association of A1C with beta-cell dysfunction, insulin resistance, and cardiovascular risk factors in Koreans with the relatively high risk for the future development of diabetes. This cross-sectional study recruited subjects from the pre-diabetic cohort of the Korea National Diabetes Program. Among study subjects (n = 616) aged 21-77 years with a history of hyperglycemia (fasting plasma glucose (FPG) ≥ 5.5 mmol/mL), analyses were conducted on 504 participants (296 women, 208 men) except for subjects with FPG ≥ 7.0 mmol/L or 120-min post-challenge plasma glucose ≥ 11.1 mmol/L or A1C ≥ 6.5 %. For insulin sensitivity and β-cell function classified by the categories of A1C levels, ∆Ins(30-0)/∆Glu(30-0) was lower in the highest quartile group than other groups. Although there was no significant difference in HOMA-IR according to the A1C categories, even lowest A1C group (≤ 5.3 %) already included many subjects with abnormal glucose tolerance. A1C showed a significant association with hsCRP, number of metabolic syndrome (MetS) components and ∆Ins(30-0)/∆Glu(30-0) after adjusting for age, gender, BMI, and medications whereas HOMA-IR was insignificantly associated with A1C. Stepwise regression analysis for A1C showed that A1C is independently and negatively associated with ∆Ins(30-0)/∆Glu(30-0), and positively associated with hsCRP. Our study showed that higher A1C was associated with impaired early-phase insulin secretion, MetS, and low grade inflammation in Koreans with the relatively high risk for the future development of diabetes.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Korea University Guro Hospital, 80 Guro-Dong, Guro-Gu, Seoul, 152-050, Korea.
authors.forename: Tae Nyun
authors.initials: TN
authors.lastname: Kim
authors.forename: Man Sik
authors.initials: MS
authors.lastname: Park
authors.forename: Seong Keon
authors.initials: SK
authors.lastname: Lee
authors.forename: Sae Jeong
authors.initials: SJ
authors.lastname: Yang
authors.forename: Kwan Woo
authors.initials: KW
authors.lastname: Lee
authors.forename: Moonsuk
authors.initials: M
authors.lastname: Nam
authors.forename: Moon Suk
authors.initials: MS
authors.lastname: Nam
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Park
authors.forename: Jeong-Taek
authors.initials: JT
authors.lastname: Woo
authors.forename: Jeong Taek
authors.initials: JT
authors.lastname: Woo
authors.forename: Young Seol
authors.initials: YS
authors.lastname: Kim
authors.forename: Sei Hyun
authors.initials: SH
authors.lastname: Baik
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000235:genetics*; D000078790:Insulin Secretion; D007723:Korea / Q000453:epidemiology; D008055:Lipids / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000453:epidemiology / Q000235:genetics; D008875:Middle Aged; D010186:Pancreatic Function Tests; D012044:Regression Analysis; D012307:Risk Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007328:Insulin; D008055:Lipids