Tohoku J. Exp. Med., 2014 October, 234(2)

Obesity Modifies the Association between Serum 25-Hydroxyvitamin D and Insulin Resistance in Korean General Population without Increased Fasting Glucose Levels

SUNG WOO LEE,¹ MYOUNGHEE KIM,² HO KIM,³ SEUNG SEOK HAN,⁴ HAJEONG LEE,⁴ JUNG PYO LEE,⁵ DONG KI KIM,⁴ CHUN SOO LIM,⁵ YON SU KIM,⁴ AE KYUNG PARK⁶ and KWON WOOK JOO⁴

¹Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea
²Department of Dental Hygiene, College of Health Science, Eulji University, Seongnam, Gyeonggi-do, Korea
³Department of Epidemiology and Biostatistics, School of Public Health, Seoul National University, Seoul, Korea
⁴Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
⁵Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, Korea
⁶College of Pharmacy, Suncheon National University, Suncheon, Junranam-do, Korea

The inverse relationship between 25-hydroxyvitamin D [25(OH)D] status and insulin resistance (IR) has been reported, but many interventional studies failed to reduce IR with 25(OH)D supplementation. In addition, there has been a paucity of literature on the interaction between 25(OH)D status and IR according to the degree of obesity in Asian subjects. We therefore evaluated the association between 25(OH)D status and IR according to the degree of obesity. Data from the Korea National Health and Nutrition Examination Survey in 2008-2010 were analyzed. The study subjects comprised 10,629 participants aged ≥ 20 years with fasting glucose < 100 mg/dL. IR was estimated by the homeostasis model assessment (HOMA). We found an inverse linear association between 25(OH)D and log_e(HOMA-IR) in multiple linear regression analysis; namely, 10 ng/mL increase of 25(OH)D was associated with 0.018 decrease of log_e(HOMA-IR) (p < 0.0001). In the subgroup analysis, we identified a distinct trend that the inverse linear association between 25(OH)D and log_e(HOMA-IR) became more prominent with the progression of body mass index, waist circumference, or fat mass quartile (Q): −0.009, −0.004, −0.029 and −0.037 in Q1-Q4 of body mass index, −0.004, −0.014, −0.02 and −0.038 in Q1-Q4 of waist circumference, and −0.002, −0.001, −0.017 and −0.025 in Q1-Q4 of fat mass. Thus, the IR-lowering effect of 25(OH)D became more evident with the progression of obesity in an adult Korean population without increased fasting glucose levels. We suggest that proper supplementation of vitamin D might be beneficial in obese Korean adults.

keywords —— insulin resistance; metabolic syndrome; normoglycemia; obesity; vitamin D

© 2014 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2014, 234, 89-97

Correspondence: Kwon Wook Joo, M.D., Ph.D., Department of Internal Medicine, Seoul National University College of Medicine, 101 Daehakro, Jongno-gu, Seoul 110-744, Korea.

e-mail: junephro@snu.ac.kr

Correspondence:Ae Kyung Park, Ph.D., College of Pharmacy, Suncheon National University, 255 Jungangro, Suncheon 540-950, Korea.

e-mail: parkak11@sunchon.ac.kr