In this study, cord blood preptin levels in infants with high or low birth weight will be compared to those in infants with normal birth weight. Our aim is to determine whether there is a relationship between birth weight and preptin levels. Additionally, we plan to compare the cord blood preptin levels of infants of diabetic mothers with those of normal birth weight infants.

Preptin is the youngest identified member of the insulin family. It is a 34-amino acid protein derived from the E-peptide of pro-insulin-like growth factor 2. Preptin was first isolated in 2001 from the β-cell islet granules of the rat pancreas. It is co-secreted with insulin. In vitro studies have shown that preptin enhances insulin secretion in a dose-dependent manner under high glucose conditions; however, this effect is not observed under normal conditions. Nevertheless, the systemic effects of preptin on glucose metabolism are still not fully understood.

Initial clinical studies have found higher plasma preptin concentrations in patients with type 2 diabetes mellitus compared to individuals with impaired glucose tolerance and healthy controls. Moreover, preptin is linked to insulin resistance by enhancing glucose-mediated insulin secretion. Consequently, elevated preptin levels have been observed in insulin resistance-related conditions such as polycystic ovary syndrome, gestational diabetes, and type 2 diabetes mellitus. In a study serum preptin levels in pregnant women with gestational diabetes were found to be significantly higher than in the control group.

Existing studies on preptin in the literature primarily focus on adults, and there is no comprehensive research on preptin levels in newborns. Based on the available literature, the investigator study aims to compare cord blood preptin levels in infants with high or low birth weight for gestational age and infants of diabetic mothers with those of normal birth weight infants. Through this comparison, The investigators seek to determine whether there is a relationship between preptin levels and an infant's birth weight or the presence of gestational diabetes in the mother.

Between March 2025 and November 2025, mothers of infants born at Konya City Hospital who have either high or low birth weight for their gestational age or are infants of diabetic mothers (study group) will be informed about the study. If they agree to participate, written informed consent will be obtained. Similarly, during the same period, mothers of infants estimated to have normal birth weight for their gestational age (control group) will be informed about the study, and written informed consent will be obtained if they agree to participate.

Blood samples collected from the umbilical cord at birth will be processed in the biochemistry laboratory, and the serum will be separated and stored at -80°C. After reaching the target sample size, preptin levels will be analyzed. The cost of the kits used for the preptin test will be covered by the researchers.

The demographic and clinical characteristics of the patients, as well as prenatal and postnatal risk factors, will be recorded in a patient data collection form. In the investigator's study, preptin levels will be examined in infants of diabetic mothers, infants with high birth weight from healthy mothers, normal birth weight infants, and infants with low birth weight for their gestational age.

No invasive procedures or additional blood sampling will be performed on the patients for the study. The blood samples used will be obtained from residual umbilical cord blood collected for routine tests such as blood gas analysis and blood typing.

Inclusion Criteria:

• Large-for-Gestational-Age (LGA) Infants
• Appropriate-for-Gestational-Age (AGA) Infants
• Small-for-Gestational-Age (SGA) Infants
• Infants of Diabetic Mothers (IDM)

Exclusion Criteria:

• Infants with a syndromic appearance or any accompanying disease
• Infants whose families did not provide consent

Once the study is published as a scientific article, it can be shared.