Serum spexin in first-degree relatives of patients with type 2 diabetes

Abstract

Background and aims

Genetic defects significantly contribute to diabetes development, especially in genetically predisposed individuals. First-degree relatives (FDRs) of type 2 diabetes (T2D) patients face an increased risk of developing diabetes. Spexin, a novel neuropeptide, is emerging as a key player in metabolic diseases due to its role in energy homeostasis. This study aims to evaluate, for the first time, serum spexin levels in normoglycemic FDRs of T2D patients, compared to T2D and healthy controls. It also investigates the relationship between spexin levels, insulin resistance, and metabolic parameters.

Methods

Ninety participants were included: 30 with T2D, 35 normoglycemic FDRs of T2D patients, and 25 healthy controls. Serum spexin levels were measured using ELISA, along with and glycemic parameters, lipid profiles, and insulin resistance markers.

Results

Spexin levels were significantly lower in FDRs compared to controls and even lower in T2D patients, indicating a progressive decline from healthy individuals to those with T2D. Spexin levels negatively correlated with BMI, triglycerides, total cholesterol, LDL-C, fasting blood glucose, insulin, HbA1c, and HOMA-IR, but positively correlated with HDL-C.

Conclusion

Lower spexin levels in FDRs of T2D patients may be associated with a higher risk of developing T2D. Spexin levels showed statistically significant negative correlations with key metabolic and cardiovascular risk factors, including BMI (r = −0.302), triglycerides (r = −0.464), total cholesterol (r = −0.524), fasting insulin (r = −0.703), and HOMA-IR (r = −0.565), suggesting that reduced spexin may reflect or contribute to worsening metabolic health and insulin resistance. Monitoring spexin could be useful for identifying individuals at higher risk for T2D and related metabolic disorders.

Resumen

Antecedentes y objetivos

Los defectos genéticos contribuyen significativamente al desarrollo de la diabetes, especialmente en individuos genéticamente predispuestos. Los familiares de primer grado (FDR, por sus siglas en inglés) de pacientes con diabetes tipo 2 (T2D) enfrentan un mayor riesgo de desarrollar diabetes. El spexin, un neuropéptido novedoso, está emergiendo como un actor clave en las enfermedades metabólicas debido a su papel en la homeostasis energética. Este estudio tiene como objetivo evaluar, por primera vez, los niveles de spexin sérico en FDR normoglucémicos de pacientes con T2D, en comparación con pacientes con T2D y controles saludables. También investiga la relación entre los niveles de spexin, la resistencia a la insulina y los parámetros metabólicos.

Métodos se incluyeron

90 participantes: 30 con T2D, 35 FDR normoglucémicos de pacientes con T2D y 25 controles saludables. Los niveles de spexin sérico se midieron mediante ELISA, junto con parámetros glucémicos, perfiles lipídicos y marcadores de resistencia a la insulina.

Resultados

Los niveles de spexin fueron significativamente más bajos en los FDR en comparación con los controles y aún más bajos en los pacientes con T2D, lo que indica un descenso progresivo desde los individuos saludables hasta aquellos con T2D. Los niveles de spexin se correlacionaron negativamente con el IMC, los triglicéridos, el colesterol total, el LDL-C, la glucosa en ayunas, la insulina, la HbA1c y el HOMA-IR, pero se correlacionaron positivamente con el HDL-C.

Conclusión

Los niveles más bajos de spexin en los FDR de pacientes con T2D pueden estar asociados con un mayor riesgo de desarrollar T2D. Los niveles de spexin mostraron correlaciones negativas estadísticamente significativas con factores clave de riesgo metabólico y cardiovascular, incluyendo IMC (r = -0.302), triglicéridos (r = -0.464), colesterol total (r = -0.524), insulina en ayunas (r = -0.703) y HOMA-IR (r = -0.565), lo que sugiere que la reducción de spexin podría reflejar o contribuir al deterioro de la salud metabólica y la resistencia a la insulina. La monitorización de spexin podría ser útil para identificar a individuos con mayor riesgo de desarrollar T2D y trastornos metabólicos relacionados.

Introduction

Type 2 diabetes (T2D) is a significant global health concern, greatly contributing to worldwide morbidity and mortality, which makes the early identification of risk factors crucial for prevention and management efforts.¹ Over recent decades, the prevalence of T2D has increased significantly. According to the Global Burden of Disease Study 2021, the number of people living with diabetes worldwide was 529 million in 2021 and is projected to exceed 1.31 billion by 2050.² T2D is primarily caused by a progressive decline in insulin secretion and increasing insulin resistance, and it is influenced by numerous risk factors, including age, ethnicity, family history, socioeconomic status, obesity, metabolic syndrome, and unhealthy lifestyle habits.³

These risk factors contribute to T2D through complex gene-environment interactions that differ across populations. Genetic predisposition plays a critical role, as several genetic abnormalities have been identified that impair insulin function, contributing to the development of T2D in susceptible individuals.⁴ First-degree relatives (FDRs) of T2D patients are particularly at high risk due to genetic predispositions to insulin resistance and associated metabolic disorders such as overweight/obesity, hyperglycemia, and dyslipidemia. In FDRs, these genetic factors may also alter cytokine gene transcription, leading to abnormalities in cytokine secretion and metabolism. Elevated levels of adipokines found in FDR may be linked to impaired insulin function, further increasing their risk for developing diabetes or pre-diabetes.⁵

The underlying mechanisms for these elevated risks include insulin resistance and beta cell dysfunction, which are often present in FDRs even before the onset of clinical hyperglycemia. Given that insulin-stimulated glucose uptake by adipose tissue is limited, yet plays a crucial role in whole-body energy homeostasis, the exploration of new cytokines like spexin, which may influence insulin sensitivity, is particularly relevant.⁶

Spexin, a newly discovered 14-amino acid neuropeptide identified through bioinformatics mining of the human proteome, is widely expressed in the endocrine systems of humans and animals. It is present in the central and peripheral nervous systems, visceral fat, liver, kidney, thyroid, and pancreatic islets, suggesting a role in glucose metabolism regulation. Previous clinical studies have reported changes in plasma spexin levels in individuals with T1D, T2D, and metabolic syndrome, indicating its potential involvement in metabolic disorders.^7,8 However, whether low spexin levels represent a primary or secondary phenomenon in T2D, and their relationship with metabolic markers, remains unclear.

This study aims to investigate the serum levels of spexin in normoglycemic FDRs of T2D patients and their potential association with metabolic markers, to better understand the role of spexin in the pathogenesis of T2D.

Subjects and methods

This cross-sectional study was conducted with 30 patients diagnosed with T2D, 35 first-degree relatives of T2D patients, and 25 healthy age- and sex-matched controls. Participants were recruited from the Diabetes and Endocrine Outpatient Clinic at Police Hospital, Nasr City, Cairo, over a 6-month period.

Participants included adults aged 18 years or older, of both sexes. Patients with T2D were diagnosed according to the American Diabetes Association 2023 criteria, defined as fasting blood glucose (FBG) ≥ 126 mg/dL and/or glycated hemoglobin (HbA1c) ≥ 6.5%.⁹ FDRs were normoglycemic individuals with a confirmed first-degree relationship to a T2D patient. Healthy controls were individuals with no personal or family history of diabetes, matched for age and sex.

Exclusion criteria: Patients with renal, hepatic, cardiac, pulmonary, or thyroid disorders, as well as those with serious physical disabilities, learning disorders, severe communication barriers, or pregnant women, were excluded from the study.

Prior to enrollment, all participants provided written informed consent after receiving a detailed explanation of the study's objectives, procedures, and potential risks. Personal identifiers were kept confidential. The study protocol and related documentation were approved by Research Ethics Committee of Faculty of Medicine for Girls (FMG-IRB), Al-Azhar University, Cairo, with approval number 1671 ensuring compliance with Declaration of Helsinki and World Health Organization guidelines.

Clinical and biochemical evaluation

Participants underwent a comprehensive evaluation, including physical examination and detailed medical history focusing on family history of diabetes and duration of diabetes in T2D subjects. Additionally, detailed clinical examination, anthropometric and blood pressure measurement were done.

Fasting blood samples were collected aseptically from all subjects for laboratory analysis. Routine enzymatic methods were used to measure fasting blood glucose (FBG), serum total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG). EDTA-treated blood was used to measure glycated hemoglobin (HbA1c) calorimetrically using cation exchange resin.

Serum spexin and insulin were measured using ELISA kits supplied by Bioassay Technology Lab, Shanghai, China and Bio-Rad Laboratories Inc., the United States, respectively.

Statistical analysis

Data were entered, edited, and analyzed using IBM SPSS Statistics Version 23. Normality of data was checked by Kolmogorov–Smirnov Z. Quantitative data were expressed as mean ± standard deviation while qualitative variables were presented as number (percentage). The comparison between groups with qualitative data was done by using Chi-square test while the comparison between more than two groups with quantitative data and parametric distribution were done by using one-way ANOVA test followed by post hoc analysis using LSD test. While the comparison between more than two groups with quantitative data and non-parametric distribution was done by using Kruskal–Wallis test followed by post hoc analysis using Mann–Whitney test.

Spearman correlation coefficients were used to assess the correlation between spexin and other parameters in all participants. Receiver operating characteristic curve (ROC) was used to assess the best cut off point to differentiate between normoglycemic and T2D individuals.

Univariate and multivariate logistic regression analyses were used to identify key factors associated with T2D with its odds ratio (OR) and 95% Confidence interval (CI).

Results

The clinical, anthropometric, and biochemical features of the groups under study are shown in Table 1. Spexin levels were significantly lower in both T2D patients and their FDRs compared to healthy controls, with the most pronounced reduction observed in the T2D group. The decrease in spexin was statistically significant between all three groups, highlighting its potential role as a biomarker for metabolic disturbances associated with T2D.

Table 1.

Demographic, clinical, and biochemical characteristics of the studied groups.

Groups	T2D patients (n = 30)	FDRs of T2D patients (n = 35)	Control (n = 25)	P-value	Post hoc analysis
Variables
Age (years)	45.9 ± 9.52	39.4 ± 9.96	44.9 ± 16.5	0.070	–
Gender
Females	22 (73.3%)	17 (48.6%)	15 (60.0%)	–	–
Males	8 (26.7%)	18 (51.4%)	10 (40.0%)		–
Family pedigree for diabetes
Mother	22 (62.9)	31 (88.6)	–	0.114	–
Father	10 (28.6%)	12 (34.3%)	–	0.933	–
Siblings	11 (31.4%)	0 (0.0%)	–	<0.001**	–
Weight (kg)	80.9 ± 5.92	79 ± 6.54	78.09 ± 8.63	0.311	–
Height (cm)	165.53 ± 6.34	166.57 ± 6.55	167.5 ± 7.63	0.571	–
BMI (kg/m^2)	29.33 ± 1.00	28.57 ± 1.09	28.96 ± 1.74	0.062	–
WC (cm)	82.84 ± 5.18	76.73 ± 5.58	77.44 ± 6.59	<0.001**	P1 = 0.002*P2 = 0.654P3 < 0.001*
SBP (mmHg)	131.67 ± 7.47	125.71 ± 6.08	116.8 ± 4.30	<0.001**	P1 = <0.001*P2 = <0.001*P3 < 0.001*
DBP (mmHg)	85.00 ± 5.72	80.57 ± 2.36	76.8 ± 11.45	0.001**	P1 < 0.001*P2 = 0.043*P3 = 0.013*
TG (mmol/L)	4.19 ± 1.03	4.17 ± 1.22	3.06 ± 0.73	<0.001**	P1 < 0.001*P2 < 0.001*P3 = 0.921
Total cholesterol (mmol/L)	5.32 ± 0.75	4.92 ± 0.84	3.93 ± 0.77	<0.001**	P1 < 0.001*P2 < 0.001*P3 = 0.051
LDL-C (mmol/L)	6.22 ± 1.46	6.12 ± 1.38	5.08 ± 0.63	0.002**	P1 = 0.001*P2 = 0.002*P3 = 0.777
HDL-C (mmol/L)	1.93 ± 0.21	2.47 ± 0.26	2.53 ± 0.31	<0.001**	P1 < 0.001*P2 = 0.333P3 < 0.001*
FBG (mmol/L)	10.58 ± 3.85	5.27 ± 0.39	5.05 ± 0.56	<0.001**	P1 < 0.001*P2 = 0.704P3 < 0.001*
HbA1c (%)	8.35 ± 0.9	5.02 ± 0.43	4.9 ± 0.44	<0.001**	P1 < 0.001*P2 = 0.454P3 < 0.001*
Fasting insulin (mIU/L)	24.93 ± 3.38	15.86 ± 3.31	9.44 ± 2.33	<0.001**	P1 < 0.001*P2 < 0.001*P3 < 0.001*
HOMA-IR	3.02 ± 0.54	1.97 ± 0.37	1.60 ± 0.46	<0.001**	P1 < 0.001*P2 = 0.002*P3 < 0.001*
Spexin (ng/L)	389.1 ± 130.5	686.7 ± 155.8	869.5 ± 175	<0.001**	P1 < 0.001*P2 < 0.001*P3 < 0.001*

T2D: type 2 diabetes, FDR: first-degree relatives, BMI: body mass index, WC: waist circumference, SBP: systolic blood pressure, DBP: diastolic blood pressure, TG: triglycerides, LDL-C: low density lipoprotein cholesterol, HDL-C: high density lipoprotein cholesterol, FBG: fasting blood glucose, HbA1c: glycated hemoglobin, HOMA-IR: Homeostatic Model Assessment of Insulin Resistance.

Data are expressed as mean ± SD or number (%).

Chi-square test, one way analysis of variance followed by post hoc analysis by LSD and Kruskal–Wallis test followed by Mann–Whitney test were performed.

P1: Comparison between control group and T2D group.

P2: Comparison between control group and FDRs group.

P3: Comparison between T2D and FDRs group.

*

Significant at P-value < 0.05.

**

Significant at P-value < 0.01.

In addition to reduced spexin levels, FDRs demonstrated significantly higher levels of low-LDL-C and triglycerides compared to the control group. This suggests that FDRs, despite not having a T2D diagnosis, already show signs of an adverse lipid profile that may predispose them to future metabolic disturbances.

The correlations between serum spexin levels and the other studied parameters in all study participants are shown in Table 2. A statistically significant negative correlation was observed between spexin levels and various metabolic and cardiovascular risk factors. Lower spexin levels were negatively associated with weight, BMI, WC, blood pressure, triglyceride levels, total cholesterol, LDL-C, fasting blood glucose, fasting insulin, HbA1c, and HOMA-IR. Conversely, a positive correlation was found between spexin levels and HDL-C among all subjects.

Table 2.

Correlation between serum spexin level and the other studied parameters in all participants.

Clinical & laboratory variables	Spexin level
	R	P-value
Age (years)	0.025	0.816
Weight (kg)	−0.226	0.032*
Height (cm)	0.026	0.809
BMI (kg/m^2)	−0.302	0.004*
Waist circumference (cm)	−0.411	<0.001*
SBP (mmHg)	−0.508	<0.001*
DBP (mmHg)	−0.444	<0.001*
TG (mmol/L)	−0.464	<0.001*
Total Cholesterol (mmol/L)	−0.524	<0.001*
LDL-C (mmol/L)	−0.277	0.008*
HDL-C (mmol/L)	0.761	<0.001*
FBG (mmol/L)	−0.710	<0.001*
HbA1c (%)	−0.671	<0.001*
Fasting insulin (mIU/L)	−0.703	<0.001*
HOMA-IR	−0.565	<0.001*

BMI: body mass index, WC: waist circumference, SBP: systolic blood pressure, DBP: diastolic blood pressure, TG: triglycerides, LDL-C: low density lipoprotein cholesterol, HDL-C: high density lipoprotein cholesterol, FBG: fasting blood glucose, HbA1c: glycated hemoglobin, HOMA-IR: Homeostatic Model Assessment of Insulin Resistance.

Spearman correlation coefficients was performed.

*

Significant at P-value < 0.05.

Univariate logistic regression analysis in our study identified triglycerides, total cholesterol, LDL-C, and spexin levels as most factors associated with T2D. In multivariate logistic regression analysis using the Backward-Wald method, spexin level emerged as the strongest independent predictor of T2D. The odds ratio was 0.979 (95% confidence interval: 0.958–0.999), with a statistically significant P-value of 0.043 as shown in Table 3. These findings support the relevance of spexin in the metabolic profile of these patients.

Table 3.

Univariate and multivariate logistic regression analysis (using Backward–Wald method) for factors associated with T2D group.

Parameters	Univariate			Multivariate (Backward–Wald)^a
	OR	95% CI	P-value	OR	95% CI	P-value
TG (mmol/L)	1.036	1.0154–1.056	0.001*	–	–	–
Total cholesterol (mmol/L)	1.126	1.045–1.214	0.002*	1.279	0.966–1.692	0.085
LDL-C (mmol/L)	1.083	1.024–1.145	0.005*	–	–	–
HDL-C (mmol/L)	0.224	0.038–1.307	0.097	–	–	–
Spexin (ng/L)	0.989	0.984–0.994	<0.0001*	0.979	0.958–0.999	0.043*

TG: triglycerides, LDL-C: low density lipoprotein cholesterol, HDL-C: high density lipoprotein cholesterol, OR: odds ratio, CI: confidence interval.

a

Adjusted for age and sex.

*

Significant at P-value < 0.05.

A cutoff value of spexin ≤ 485 ng/L was identified as an effective threshold for distinguishing individuals with T2D from those without diabetes, demonstrating a sensitivity of 90%, specificity of 85.7%, and an area under the curve of 0.92 (95% CI: 0.87–0.96) as shown in Fig. 1.

Figure 1.

Receiver operating characteristic curve (ROC) for spexin as a classifier predictor for T2D (AUC is 0.92 (95% CI: 0.87–0.96)).

Discussion

Type 2 diabetes is characterized by insulin resistance and hyperinsulinemia and often remains asymptomatic for years.¹⁰ A family history of diabetes reflects both genetic and environmental factors, providing better predictive value for T2D incidence than genetic or environmental factors alone. FDRs of T2D patients may have genetic defects affecting cytokine transcription, leading to altered cytokine metabolism and secretion. Previous studies have also demonstrated increased levels of adipokines in FDRs of T2D, possibly due to impaired insulin function.¹¹

Spexin, a highly conserved 14-amino acid peptide, plays a critical role in regulating energy homeostasis, glucose and lipid metabolism, cardiovascular function, and more. It has been recognized as a regulator of obesity and metabolic disorders, including insulin resistance and T2D. Insulin and spexin localization has been identified in β cells of pigs and humans, but not in mice. This suggests that spexin may potentially influence pancreatic function.¹²

This study is the first to evaluate serum spexin levels in normoglycemic individuals that are FDRs of T2D patients. We found that spexin levels were significantly lower in FDRs compared to controls, with an even greater reduction in T2D patients.

Our findings are consistent with previous studies that reported significantly lower serum spexin levels in diabetic patients, suggesting spexin's involvement in glucose metabolism. For example, Dai et al., ⁷ Tejaswi et al.,⁸ Karaca et al.,¹³ and Al-Daghri et al.¹⁴ found decreased spexin levels in T2D patients compared to controls. It has been also found that the expression of spexin changes when diseases progress as decreased spexin levels were observed in T2D patients and were further decreased in T2D patients with cardiovascular disease compared to the levels in controls,⁸ indicating spexin as a potential early biomarker for T2D and its complications, such as cardiovascular diseases. Spexin is thought to protect against insulin resistance, enhance glucose uptake by muscle cells, suppress hepatic gluconeogenesis, reduce inflammation and oxidative stress, and improve lipid metabolism.

Insulin resistance is characterized by disruptions in key molecular pathways, including impaired insulin receptor signaling, IRS phosphorylation, and PI3K-AKT pathway activation.^15,16 Additionally, mitochondrial dysfunction and lipid accumulation play critical roles in skeletal muscle and hepatic insulin resistance.¹⁷ These insights provide a deeper understanding of the pathophysiology underlying T2D and highlight potential therapeutic targets.

In addition to spexin, several emerging biomarkers have been identified as potential predictors of T2D risk and progression. Wang et al. (2020) demonstrated that a panel of metabolic and inflammatory biomarkers such as TG-to-HDL ratio, ALT, ferritin, and adiponectin significantly improved T2D risk prediction in a Singapore Chinese population.¹⁷ Le et al. (2025) conducted a systematic review analyzing key circulating biomarkers in T2D, including hematological, protein, cytokine, and lipid profiles. Their findings highlighted significant alterations in inflammatory markers, lipid metabolites, and cytokine levels, which are associated with insulin resistance, metabolic dysfunction, and disease progression.¹⁸ Additionally, circulating microRNAs have gained attention as clinically useful biomarkers for T2D, with evidence suggesting their role in metabolic regulation, β-cell function, and insulin signaling.¹⁹ Given spexin's role in metabolic homeostasis and insulin sensitivity, future research should explore its potential interactions with these emerging biomarkers to better understand their collective impact on T2D pathophysiology.

Several mechanisms may explain how spexin influences T2D, including its protective effects against insulin resistance and its ability to increase glucose consumption in skeletal muscles via the GAL2/GLUT4 pathway, as demonstrated in previous in vitro and in vivo studies.²⁰ However, further experimental studies are required to confirm their role, especially in the context of FDRs of T2D patients. Also spexin was found to suppress hepatic gluconeogenesis and increase glucose uptake by muscle cells, reduce inflammation and oxidative stress and improve lipid metabolism.²¹

Growing evidence indicates that the genetic background of FDRs of T2D influences insulin resistance, which in turn raises their risk of metabolic complications, including such as overweight/obesity, hyperglycemia, and dyslipidemia.²² This genetic predisposition may also influence the levels of certain peptides, such as spexin, which are known to play a role in energy homeostasis and metabolic regulation; lower spexin levels in FDR of T2D could thus be a contributing factor to the insulin resistance observed in this population. Additionally, insulin resistance in FDRs suggests that it precedes the development of pancreatic β-cell dysfunction in individuals at risk for T2D.²³

In the current study, fasting insulin and HbA1c were found to be significantly increased in FDR of T2D than control group. In agreement with our results Purnamasari et al.²⁴ found significantly higher insulin levels and HOMA-IR value in FDRs of T2D group compared to non-FDR. Even with similar metabolic and anthropometric characteristics, FDRs of T2D were more hyperinsulinemic and insulin resistant, indicating a greater risk for insulin resistance-related disorders, such as diabetes, dyslipidemia, and coagulation disorders. Ahmed et al.²³ also found that glycoproteins, HbA1c and fructosamine, insulin and HOMA-IR were significantly higher in FDRs of T2D compared to controls. Similarly Liu et al.,²⁵ Sathiyapriya et al.,²⁶ and Shahid et al.²⁷ found increased fasting insulin levels, higher HOMA-IR values, and reduced insulin sensitivity in FDRs of T2D patients. FDRs of T2D are prone to insulin resistance due to impaired glucose metabolism, mitochondrial defects, and reduced insulin receptor signaling.

Studies such as those by Tsenkova et al.²⁸ and Rodríguez-Moran et al.²⁹ emphasize that a family history of diabetes is a strong, independent risk factor for T2D and impaired fasting glucose, even in the absence of diabetes. Both insulin resistance and β-cell dysfunction have been documented in FDRs of T2D, even in those without diabetes.

Lipid profile analysis revealed significantly higher levels of triglycerides, total cholesterol, and LDL-C in T2D patients and their FDRs compared to controls. These findings are consistent with prior studies.^24,30,31

The etiology of dyslipidemia in FDRs of T2D involves a complex interplay of genetic, metabolic, and lifestyle factors. Shared genetic variations may affect lipid metabolism, including cholesterol and triglyceride production, clearance, and storage.³² Insulin resistance, commonly seen in FDRs of T2D, is a significant predictor of dyslipidemia. Dyslipidemia may also result from the effects of adipocytokines such as adiponectin and spexin on insulin sensitivity. Shared dietary habits, such as high-fat diets, can exacerbate dyslipidemia in FDRs of T2D.³³ Assessing lipid profiles in FDRs may help reduce disease progression risk and facilitate early intervention.

Our study found statistically significant negative correlations between spexin levels and weight, BMI, waist circumference, blood pressure, triglycerides, total cholesterol, LDL-C, fasting glucose, insulin, HbA1c, and HOMA-IR, while a positive correlation was observed with HDL-C. These findings are consistent with those of Mashaal et al.,³⁰ Karaca et al.,¹³ Al-Daghri et al.,¹⁴ and Bitarafan et al.,³⁴ who reported similar correlations between spexin levels and metabolic risk factors. Dai et al.⁷ and Gu et al.³¹ also identified negative correlations between spexin levels and fasting glucose, HbA1c, and triglycerides.

The observed effects of spexin may be mediated through its receptor, GALR3, which regulates cholesterol and triglyceride levels in mice.³⁵ Spexin has been shown to reduce hepatic lipids, bile acids, and cholesterol metabolism, suppressing CYP7A1 expression. Spexin also co-localizes with insulin in β-cells, suggesting its potential role in modulating insulin secretion.¹² Moreover, spexin's activation of GALR2/3 receptors may help reduce insulin resistance by promoting GLUT4 translocation to plasma membranes in adipocytes.³⁶

The study has several limitations, including the relatively small sample size. Additionally, the study focused exclusively on T2D patients and their FDRs, limiting the applicability of the findings to this specific population and potentially excluding type 1 diabetes. Our study population was recruited from a single medical center in Cairo, which may limit the generalizability of our findings to other regions and ethnicities. Future studies should include more diverse populations to confirm these results. The absence of data on lifestyle factors such as physical activity and dietary habits is a limitation of this study. These factors are known to influence spexin levels and could potentially confound our results. Future studies should incorporate detailed assessments of these lifestyle factors to better understand their impact on spexin levels in FDRs of T2D patients. Lastly, the study's design does not allow for a precise determination of causal relationships.

Conclusion

Our study focuses on the role of spexin in FDRs of T2D. The findings underscore a significant decrease in serum spexin levels among FDRs of T2D, which correlates strongly with markers of insulin resistance and lipid abnormalities. Lower spexin levels in FDRs of T2D patients may suggest an increased risk for T2D, but this finding should be considered preliminary. Further research, particularly longitudinal studies, is needed to confirm the potential of spexin as an early indicator of T2D risk and to elucidate the underlying mechanisms.

The association between low spexin levels and insulin resistance suggests that spexin may play a critical role in glucose metabolism and lipid homeostasis. Insulin resistance, a hallmark of T2D, often precedes the clinical onset of the disease by several years. Thus, the identification of low serum spexin levels in FDRs of T2D provides a valuable predictor for early intervention.

Lipid abnormalities, which are also associated with reduced spexin levels, further exacerbate the risk of developing T2D. These findings highlight the importance of monitoring spexin levels in FDRs of T2D as part of a comprehensive strategy to identify individuals at high risk of T2D. Early detection of decreased spexin levels allows for timely lifestyle and pharmacological interventions aimed at improving insulin sensitivity and lipid profiles, thereby reducing the prevalence of T2D.

Authors’ contribution

Conception and design: EM. Investigation: MAS and SMA. Methodology: MAS and EGK. Manuscript writing: MAS and EGK. Review & editing: EM and SMA. All authors have read and approved the published version of the manuscript.

Ethics approval and consent to participate

The study was approved by the Research Ethics Committee of Faculty of Medicine for Girls (FMG-IRB), Al-Azhar University, Cairo, with approval number 1671 at 04/01/2023 ensuring compliance with Declaration of Helsinki and World Health Organization guidelines.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of interests

The authors declared that they have no conflict of interest.

Acknowledgements

We would like to express our gratitude to the managerial and nursing staff of the Department of Diabetes and Endocrine outpatient clinic at Police hospital Nasr City, Cairo who facilitated patient identification and sampling, and helped us to complete this work.