Leptin contributes to hemoglobin A1c in older adults in the Baltimore Longitudinal Study of Aging

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 758-775-Beta Cells, Glucose Control & Complications
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-765
Jenny Pena Dias*, David D. Liu, Luigi Ferrucci, Josephine Mary Egan and Chee Wei Chia
NIA/NIH, Baltimore, MD
Background: The use of hemoglobin A1c (A1c) for diagnosing diabetes has recently been adopted by the World Health Organization and the American Diabetes Association (1, 2).  A1c levels are reported to increase with age in nondiabetic populations (3).  The cause of this increase is unknown and questions the necessity of age-specific diagnostic criteria (3). Leptin affects the membrane fluidity of erythrocytes (4); therefore, we hypothesize that leptin may contribute to the age-associated increase in A1c. 

Methods: This cross-sectional analysis used data from 1185 subjects (49.7% men) who participated in the Baltimore Longitudinal Study of Aging with fasting plasma glucose (FPG) < 126 mg/dL or 2-hr plasma glucose from 75-gm oral glucose tolerance test (2hrG) < 200 mg/dL. Using multiple linear regression analysis, we tested the association between A1c and fasting plasma leptin levels adjusting for age, sex, BMI, FPG, and 2hrG. Leptin was log transformed for analyses. Data are presented as mean ± SE, except for leptin which was presented as median (interquartile range), and standardized regression coefficients (β) were used.

Results: The population characteristics are as follows:  age = 68±14 yrs; BMI = 27±5 kg/m²; A1c = 5.74 ± 0.46 %; FPG = 95.5 ± 10.3 mg/dl; 2hrG = 120.0 ± 34.2mg/dl; and leptin = 21.29±19.97 ng/ml.  Using multiple linear regression analysis, A1c was independently associated with leptin (β=0.14; P<0.001) after adjusting for age (β=0.20; P<0.001), BMI (β = -0.002, P =0.96), sex (β = -0.04, P=0.27), FPG (β =0.19; P<0.001) and 2hrG (β =0.13; P<0.001).

Conclusion: Circulating leptin levels may contribute to the age-associated increase of A1c.  Further research is needed to characterize how leptin and other as yet unknown factors contribute to the increase of A1c with age, and how best to use A1c in diagnosing diabetes in the older population.

1. World Health Organisation. Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. Geneva: World HealthOrganisation, 2011.   2.  Diagnosis and Classification of Diabetes Mellitus. Diabetes Care, January 2011.34, Supplement 1. 3. Pani, L.N., Korenda, L., Meigs, J.B., Driver, C., Chamany S., Fox, C.S., Sullivan, L., D’Agostino, R.B., Nathan, D.M. Effect of aging on A1C levels in individuals without diabetes: evidence from the Framingham Offspring Study and the National Health and Nutrition Examination Survey 2001-2004. Diabetes Care, 2008. 31(10): p. 1991-6.   4. Tsuda, K. and I. Nishio, Leptin and membrane fluidity of erythrocytes in essential hypertension. An electron paramagnetic resonance investigation. Am J Hypertens, 2004. 17(4): p. 375-9.

Nothing to Disclose: JPD, DDL, LF, JME, CWC

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: This research was supported entirely by Intramural Research Program of NIH, NIA.