Presentation on theme: "Leptin and soluble leptin receptor and risk of clinical diabetes in African- American, Hispanic, and Asian postmenopausal women. Kathleen Brennan, MD Assistant."— Presentation transcript:
Leptin and soluble leptin receptor and risk of clinical diabetes in African- American, Hispanic, and Asian postmenopausal women. Kathleen Brennan, MD Assistant Clinical Professor Department of OBGYN Division of Reproductive Endocrinology and Infertility UCLA October 17, 2013 WHI Diabetes/Obesity SIG
Menopause and Adiposity Increased waist circumference –Increase in fat mass Preferential central/abdominal fat deposition –Increased levels of adipocytokines –Increased risk of insulin resistance and cardiovascular disease Prevalence of metabolic syndrome in PMP women as high as 40-50% Sowers, et al. J Clin Endocrinol Metab Lobo. Maturitas Ford, et al. JAMA Park, et al. Arch Intern Med Carr MC. J Clin Endocrinol Metab 2003.
Leptin –Protein secreted by adipocytes –Acts on hypothalamus to regulate body weight homeostasis Increased body fat increased leptin –Leptin resistance Fasting and very low calorie diet decreased leptin –Has been implicated in various pathways leading to development of cardiovascular disease and DM Considine, et al. NEJM Di Carlo, et al. Gynecol Endocrinol Harris, et al. Endocrinology Barash, et al Endocrinolgy Chehab, et al. Nature Genet 1996.
Soluble Leptin Receptor Major leptin binding protein in the circulation Soluble leptin receptor (sOB-R) levels are low in obese individuals –Levels increase with weight loss and low-calorie diet –Majority of leptin bound in lean subjects and unbound in obese subjects Soluble leptin receptor levels are inversely proportional to leptin levels Lee et al. Nature Sinha et al. J Clin Invest Lammert et al. Biochem Biophys Res Commun Ogawa et al. Metabolism 2004.
Leptin and Diabetes Conflicting evidence regarding relationship between leptin and both insulin sensitivity and DM in humans –Leptin may suppress insulin synthesis and secretion, and increase insulin sensitivity –Increased leptin levels may be associated with insulin resistance May be a result of leptin resistance –Some population studies have reported that leptin or sOB-R levels predict the development of DM Others have not after adjusting for potential confounders (like BMI) Huerta. Rev Endocr Metab Dis Huang et al. J Biol Chem Soderberg, et al. In J Obesity Welsh et al. Diabetes Care Sun et al. Diabetes Sandhofer et al. Obes Res 2001 Ogawa et al. Metabolism Bandaru et al. Meab Syndr Relat D 2011.
Leptin and Diabetes Unclear if or how the relationship between leptin and DM is affected by adiposity, insulin resistance, or sOB-R levels. Understanding the relationships between levels of leptin or sOB-R and DM risk may have clinical implications for DM risk prediction. Sun et al. Diabetes Bandaru et al. Metab Syndr Relat D Ley et al. Diabetes Care Wannamethee et al. Diabetes Care Schmidt et al. Diabetalogia 2006.
Study Objective To investigate the prospective relationships of leptin and sOB-R on the development of DM using a nested case-control study of postmenopausal ethnic minority women in the WHI-OS. –Additionally, we further explored possible differences in the relationships between both leptin and sOB-R and DM risk on obese and non-obese women within our study population
Hypothesis Higher leptin and lower leptin receptor levels are associated with increased DM risk.
Materials and Methods 93,676 postmenopausal women Ages ,069 women free of diabetes (DM) at enrollment Questionnaires mailed annually –Incident diabetes identified by new DM treatment or hospitalization for DM
Materials and Methods 642 Black, Hispanic, or Asian/Pacific Islander women developed diabetes Matched to 1289 study participants who were free of disease –Age –Ethnicity –Clinical center –Time of blood draw –Length of follow-up
Relative risk for clinical diabetes per unit increase in leptin concentration by obesity status p-heterogeneity=0.002 A.
Relative risk for clinical diabetes per unit increase in sOB-R concentration by obesity status p-heterogeneity=0.03 B.
Results summary 1.Higher leptin and lower sOB-R levels were associated with increased DM risk. 2.These relationships were stronger in non- obese women. 3.Controlling for HOMA-IR in the multivariable models led to an inverse association between leptin levels and DM risk and a direct association between sOB- R levels and DM risk.
Concluding thoughts Leptin levels are strongly correlated to insulin resistance and may primarily serve as a marker for adiposity and related conditions. –Holding insulin resistance constant may reveal weaker, potentially protective associations between leptin levels and DM risk which are typically overshadowed by the stronger effects of adiposity or insulin resistance –Holding insulin resistance constant also reversed the association between sOB-R and DM risk
Concluding thoughts The associations between leptin and sOB-R differed in obese and non-obese women –Leptin may protect against the development of DM in obese women –Higher levels of sOB-R seem to be protective in non-obese women, but not in obese women.