الفهرس 
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Abstract
Gestational Diabetes Mellitus (GDM) is one of the most important conditions which complicates up to 14% of pregnancies worldwide. GDM patients are more frequently affected by changes in bone turnover during pregnancy. Compared with healthy pregnancies, women with GDM are at increased risk of later development of type 2 diabetes mellitus. Gestational diabetes mellitus (GDM) can serve as a model of pre-type 2diabetes. Osteocalcin, osteoblast-derived protein acting locally on bone formation, is suspected to be involved in the regulation of glucose and fat metabolism.
Our data showed that among GDM group, the mean concentration of serum osteocalcin was significantly lower than in healthy pregnant ladies.
Also, we found that there is highly significant negative correlation between serum osteocalcin level and FBS (r= -0.492) (P< 0.001), 2hr PP (r = -0.683) (P< 0.001), fasting insulin level (r= -0.761) (P< 0.001), HOMA-IR (r= -0.692) (P< 0.001), triglycerides (r= -.659) (P< 0.001), cholesterol (r= -0.563) (P< 0.001), LDL (r= -0.592) (P< 0.001) and there is highly significant positive correlation between serum osteocalcin level and HDL (r= 0.442) (P< 0.001) among the two groups.
This study had some limitations. First, this study was held on small number of cases (60 pregnant ladies). Second, we did not differentiate plasma osteocalcin with respect to the gamma-carboxylation status, and only measured the total form of osteocalcin, instead of directly measuring carboxylated and uncarboxylated osteocalcin. Therefore, we do not know the differential mechanism of both types of osteocalcin to regulate insulin secretion and insulin sensitivity. Lastly, it has been suggested that bone resorption al low PH is necessary to decarboxylate osteocalcin, and thus osteoclasts determine the carboxylatiion status and function of osteocalcin in mice (Ferron et al., 2010) and possibly in humans (Aonuma et al., 2009). Therefore, the additional measurement of bone resorption markers may further clarify the potential association between bone resorption, osteocalcin, and glucose homeostasis in humans.
In conclusion, our results showed that gestational diabetes mellitus associated with a decline in osteocalcin level during 22nd -28th weeks of gestation in comparison to normal pregnant females at same gestational weeks.