JCEM：骨钙蛋白与骨骼肌胰岛素敏感性有关

动物实验显示骨钙蛋白（OC），特别是羧基化骨钙蛋白（unOC），影响胰岛素敏感性和分泌，但是缺乏来自人类的权威数据。为了确定在超重/肥胖成年人，总OC和unOC是否与胰岛素敏感性和β细胞反应独立相关；糖耐量状态是否影响这些相关性；以及这些相关性是否独立于1型前胶原氨基端肽（P1NP）反映的骨形成。来自英国伯明翰阿拉巴马大学的Barbara A Gower教授及其团队进行了一项研究，该研究发现，在超重和肥胖个体，总OC与骨骼肌胰岛素敏感性有关。该研究结果在线发表在2013年4月24日的美国《临床内分泌代谢杂志》（The Journal of Clinical Endocrinology & Metabolism）上。

该研究是在阿拉巴马大学研究中心进行的一项横断面研究，包括63例正常（39例）或空腹血糖受损（IFG24例）的超重/肥胖成年人。通过放射免疫分析评估血清总/羧基化OC和PINP浓度；通过静脉葡萄糖耐量试验（S1–IVGTT）、液体餐试验（S1–meal）和HOMA–IR确定胰岛素敏感性；利用进餐试验数据的C肽模型推断β细胞对葡萄糖的反应（基础的，PhiB；动态的，PhiD；静态的，PhiS；和总的，PhiTOT）；使用CT扫描测量腹内脂肪组织（IAAT）。

该研究结果表明，校正IAAT和PINP后，在整个样本的多元线性回归显示总OC与S1–IVGTT呈正相关（P＜0.01）。OC与S1–meal或HOMA–IR不相关。在IFG受试者，unOC独立于胰岛素敏感性，与PhiS和PhiTOT呈正相关（P＜0.05）.

该研究发现，在超重/肥胖个体，总OC可能与骨骼肌胰岛素敏感性相关，但与肝脏胰岛素敏感性无关。仅在IFG个体，unOC与β细胞功能有独特相关性。

与胰岛素敏感性相关的拓展阅读：

• Diabetes Care: 果糖摄入降低胰岛素敏感性
• Diabetes：郭非凡等揭示下丘脑ATF4调控肝脏胰岛素敏感性的新功能
• Diabetes:早产者较足月产者胰岛素敏感性稍低
• Diabetes Care：提高胰岛素敏感性减少肥胖者食物渴求
• JCI：脂肪细胞铁水平调节脂联素和胰岛素敏感性 更多信息请点击：有关胰岛素敏感性更多资讯

Associations of total and undercarboxylated osteocalcin with peripheral
Context
Animal studies indicate that osteocalcin (OC), particularly the undercarboxylated isoform (unOC), affects insulin sensitivity and secretion, but definitive data from humans are lacking.
Objective
To determine if total OC and unOC are independently associated with insulin sensitivity and β-cell response in overweight/obese adults; whether glucose tolerance status affects these associations; and whether associations are independent of bone formation, as reflected in procollagen type 1 amino propeptide (P1NP).
Design, Setting, and Participants
This was a cross-sectional study conducted at a University Research Center involving 63 overweight/obese adults with normal (n=39) or impaired fasting glucose (IFG, n=24).
Main outcome measures
Serum concentrations of total/undercarboxylated OC and P1NP were assessed by RIA; insulin sensitivity was determined by intravenous glucose tolerance test (SI-IVGTT), liquid meal test (SI-meal), and HOMA-IR; β-cell response to glucose (basal, PhiB; dynamic, PhiD; static, PhiS; and total, PhiTOT) was derived using C-peptide modeling of meal test data; and intra-abdominal adipose tissue (IAAT) was measured using CT scanning.
Results
Multiple linear regression, adjusting for IAAT and P1NP, revealed that total OC was positively associated with SI-IVGTT (P<0.01) in the total sample. OC was not associated with SI-meal or HOMA-IR. In participants with IFG, unOC was positively associated with PhiS and PhiTOT (P<0.05) independent of insulin sensitivity.
Conclusions
In overweight/obese individuals, total OC may be associated with skeletal muscle but not hepatic insulin sensitivity. unOC is uniquely associated with β-cell function only in individuals with IFG. Further research is needed to probe the causal inference of these relationships, and to determine if indirect nutrient sensing pathways underlie these associations.