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Oxid Med Cell Longev. 2017;2017:4807046. doi: 10.1155/2017/4807046. Epub 2017 Aug 23.

Effect of Weight Loss, Exercise, or Both on Undercarboxylated Osteocalcin and Insulin Secretion in Frail, Obese Older Adults.

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Division of Endocrinology, Diabetes, and Metabolism, Baylor College of Medicine, Houston, TX 77030, USA.
Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey VA Medical Center, Houston, TX 77030, USA.
University Campus-Biomedico, 00128, Rome, Italy.



Obesity exacerbates age-related decline in glucometabolic control. Undercarboxylated osteocalcin (UcOC) regulates pancreatic insulin secretion. The long-term effect of lifestyle interventions on UcOC and insulin secretion has not been investigated.


One hundred seven frail, obese older adults were randomized into the control (N = 27), diet (N = 26), exercise (N = 26), and diet-exercise (N = 28) groups for 1 year. Main outcomes included changes in UcOC and disposition index (DI).


UcOC increased in the diet group (36 ± 11.6%) but not in the other groups (P < 0.05 between groups). Although similar increases in DI occurred in the diet-exercise and diet groups at 6 months, DI increased more in the diet-exercise group (92.4 ± 11.4%) than in the diet group (61.9 ± 15.3%) at 12 months (P < 0.05). UcOC and body composition changes predicted DI variation in the diet group only (R2 = 0.712), while adipocytokines and physical function changes contributed to DI variation in both the diet (∆R2 = 0.140 and 0.107) and diet-exercise (∆R2 = 0.427 and 0.243) groups (P < 0.05 for all).


Diet, but not exercise or both, increases UcOC, whereas both diet and diet-exercise increase DI. UcOC accounts for DI variation only during active weight loss, while adipocytokines and physical function contribute to diet-exercise-induced DI variation, highlighting different mechanisms for lifestyle-induced improvements in insulin secretion. This trial was registered with number NCT00146107.

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