Comprehensive assessment of lipoprotein subfraction profiles according to glucose metabolism status, and association with insulin resistance in subjects with early-stage impaired glucose metabolism.

BACKGROUND: Early detection of atherogenic dyslipidemia is crucial. We investigated lipoprotein subfraction parameters according to glucose metabolism status. METHODS: We recruited 1255 lipid-lowering drug-naïve subjects with normal fasting glucose (NFG; n=200, 15.9%), impaired fasting glucose (IFG; n=443, 35.3%), or type 2 diabetes (T2D; n=612, 48.8%). Lipoprotein subfractions (1-7) were determined by polyacrylamide gel electrophoresis, separating low-density lipoprotein (LDL) into large buoyant LDL (lbLDL, LDL1-2) and small dense LDL (sdLDL, LDL3-7). Lipoprotein subfraction parameters including the sdLDL% (LDL3-7/LDL1-7), the sdLDL/lbLDL ratio (LDL3-7/LDL1-2), and weighted LDL subfraction (LDLSF) scores, were compared between groups. Their associations with insulin resistance, estimated using the homeostasis model assessment of insulin resistance, were examined. RESULTS: The concentrations of sdLDL particles were significantly higher in subjects with T2D and IFG than in those with NFG (15.78±13.47mg/dl and 14.60±14.33mg/dl, respectively, vs. 12.22±12.31mg/dl). Compared with those with NFG, subjects with IFG or T2D had significantly a higher sdLDL% (15.98±15.26% vs. 19.50±16.21% or 21.46±16.81%, respectively), a higher sdLDL/lbLDL ratio (0.24±0.30 vs. 0.31±0.37 or 0.35±0.39), and a higher LDLSF score (2.08±0.91 vs. 2.30±1.14 or 2.36±1.17). These lipoprotein subfraction parameters had stronger associations with insulin resistance compared to conventional lipid profiles in the IFG and T2D groups. CONCLUSIONS: Atherogenic dyslipidemia is initiated in an early stage of impaired glucose metabolism, when early intervention might be required.

Role of various indices derived from an oral glucose tolerance test in the prediction of conversion from prediabetes to type 2 diabetes.

AIMS: The clinical implications of prediabetes for development of type 2 diabetes may differ for Asian ethnicity. We investigated various indices derived from a 2-h oral glucose tolerance test (OGTT) in people with prediabetes to predict their future risk of diabetes. METHODS: We recruited 406 consecutive subjects with prediabetes from 2005 to 2006 and followed them up every 3-6 months for up to 9 years. Prediabetes was defined as isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), combined glucose intolerance (CGI), or isolated elevated HbA1c (5.7-6.4%, 39-46 mmol/mol) without IFG or IGT. The rate of diabetes conversion was compared between prediabetes categories. The association of glycemic indices with development of diabetes was also investigated. RESULTS: Eighty-one patients were diagnosed with diabetes during the 9-year follow-up (median 46.0 months). The rate of diabetes conversion was higher in subjects with CGI (31.9%), or isolated IGT (18.5%) than in those with isolated IFG (15.2%) or isolated elevated HbA1c (10.9%). Surrogate markers reflecting ß-cell dysfunction were more closely associated with diabetes conversion than insulin resistance indices. Subjects with a 30-min postload glucose ≥ 165 mg/dL and a 30-min C-peptide < 5 ng/mL had 8.83 times greater risk (95% confidence interval 2.98-26.16) of developing diabetes than other prediabetic subjects. CONCLUSIONS: In Asians, at least Koreans, ß-cell dysfunction seems to be the major determinant for diabetes conversion. A combination of high glucose and low C-peptide levels at 30 min after OGTT may be a good predictor for diabetes conversion in this population.

Assessment of appendicular skeletal muscle mass by bioimpedance in older community-dwelling Korean adults.

It is crucial to investigate age-related body composition changes in geriatric medicine. Bioelectrical impedance analysis (BIA) is easy to perform, non-invasive, relatively inexpensive, and portable. However, the accuracy of measurement by BIA is questionable. To develop and cross-validate the predictive equation for estimated appendicular skeletal muscle mass (ASM) using BIA in older community-dwelling Korean adults, we include two cohorts: study participants aged 65-80 years in the Ansung cohort for the Korean Health and Genome Study (men, n=285; women, n=435) used as equation-generating group, and Korean Longitudinal Study of Health Aging (KLoSHA) as cross-validation group (men, n=202; women, n=208). Dual energy X-ray absorptiometry (DXA) and BIA were performed in both cohorts. Using multiple linear regression analysis, we drew a predictive equation for DXA-measured ASM by BIA resistance. From DXA and BIA measurements in the Ansung cohort, we generated the estimated equation ASM (kg)=[(Ht(2)/R×0.104)+(age×-0.050)+(gender×2.954)+(weight×0.055)]+5.663 where Ht is height in centimeters; R is BIA resistance in 250Ω; for gender, men=1 and women=0; and age is in years. We validated this equation in the KLoSHA. The r(2) of the estimated ASM was 0.890. This BIA equation provides valid estimates of ASM in older Korean adults.