The skeletal muscle plays a critical role in regulating systemic blood glucose homeostasis. Impaired skeletal muscle glucose homeostasis associated with type 2 diabetes mellitus (T2DM) has been observed to significantly affect the whole-body glucose homeostasis, thereby resulting in other diabetic complications. T2DM does not only affect skeletal muscle glucose homeostasis, but it also affects skeletal muscle structure and functional capacity. Given that T2DM is a global health burden, there is an urgent need to develop therapeutic medical therapies that will aid in the management of T2DM. Prediabetes is a prominent risk factor of T2DM that usually goes unnoticed in many individuals as it is an asymptomatic condition. Hence, research on prediabetes is essential because establishing diabetic biomarkers during the prediabetic state would aid in preventing the development of T2DM, as prediabetes is a reversible condition if it is detected in the early stages. Literature predominantly documents the changes in skeletal muscle during T2DM, but the changes in skeletal muscle during prediabetes remain unknown. In this review, we seek to review the existing literature on prediabetic and T2DM associated changes in skeletal muscle function.

Prediabetes, a pivotal phase in glucose metabolism between normalcy and diabetes, exerts a profound influence on the aging process and the risk of age-related diseases. This comprehensive review delves into the intricate web of blood-based biomarkers that collectively expedite senescence, marking the transition from a state of health to age-related complications. Key findings underscore the significance of diverse biomarkers, such as telomere length, p16INK4a, senescence-associated secretory phenotype (SASP) factors, DNA methylation clocks, advanced glycation end products (AGEs), inflammatory and oxidative stress markers, circulating hormones, and additional factors like folate, B12, osteocalcin, and more. Not only do these biomarkers serve as indicators of senescence, but they actively fuel chronic inflammation, oxidative stress, and metabolic dysregulation, all of which contribute to accelerated aging. The implications of this understanding are profound, as prediabetes emerges as a critical period in an individual's life, influencing various physiological systems, including the vascular and neural systems, metabolic functions, hormonal regulation, and bone health. Recognizing the profound influence of prediabetes on senescence provides a foundation for personalized intervention strategies to mitigate age-related complications and promote healthy aging. Future research directions call for a more diverse array of biomarkers, in-depth exploration of their roles, and the development of tailored precision medicine strategies to ensure a holistic understanding and effective management of prediabetes-induced senescence and its implications for aging. This knowledge has far-reaching implications for public health and clinical practice, emphasizing the need for early detection and intervention in prediabetic individuals to enhance the quality of life in an aging population with diverse needs.

There is a have been positive correlations between the existence of type 2 diabetes mellitus (T2DM) and the development of thyroid disorders. Prediabetes is a progressive state of moderate insulin resistance that often precedes the onset of type 2 diabetes mellitus (TT2DM) however the association between prediabetes and thyroid function is unknown. This study assessed changes in markers of thyroid function in diet-induced prediabetes. 12 male Sprague Dawley rats were randomly allocated into two groups. Rats in the non-prediabetic (NPD) group were fed a standard rat diet while rats in the prediabetic (PD) were fed a high-fat high carbohydrate diet for 20 weeks to induce prediabetes. Thereafter, fasting blood glucose levels were measured. Plasma samples were assessed for triiodothyronine (T3), thyroxine (T4), thyroxine peroxidase (TPO) antibody, insulin and glycated haemoglobin (HbA1c) concentrations. The elevated blood glucose, HbA1c and plasma insulin levels coincided with increased T3 and reduced T4 levels in the PD group when compared to the NPD group. There was also an increase in the concentration of TPO antibodies in the PD group. Additionally, there was a significant correlation between the thyroid hormone concentrations and HbA1c levels. In conclusion, these results indicated that there is a positive association between thyroid dysfunction and diet-induced prediabetes.

A growing body of research has identified fetal risk factors associated with adult diseases that form the basis for the Developmental Origins of Health and Disease (DOHaD) hypothesis. This theory proposes a critical developmental period during which the fetus is highly susceptible to specific environmental influences that significantly impact health from short to long term. Maternal stress and T2DM during pregnancy are among these influences, likely leading to fetal overexposure to glucocorticoids and suggesting a shared pathway between maternal dysregulated HPA axis and fetal environmental insults. Studies demonstrate that prenatal glucocorticoid exposure alters fetal HPA axis function, affecting brain function, tissue glucocorticoid availability, and fetal growth in utero. These programmed changes, such as altered HPA axis function and reduced fetal growth, contribute to metabolic disorders persisting into adulthood. T2DM is preceded by a prediabetic state, often asymptomatic, which shares similar pathophysiological complications with T2DM, including HPA axis dysregulation observed in animals. Therefore, investigating prediabetes during pregnancy alongside maternal HPA axis function and its effects on fetal outcomes is crucial, as these areas remain understudied. This review aims to synthesize existing literature on pre-existing T2DM during pregnancy, its links to fetal programming via HPA axis changes, and possible links to pregestational prediabetes.

Maternal type 2 diabetes mellitus (T2DM) has been shown to result in fetal programming of the hypothalamus-pituitary-adrenal (HPA) axis, leading to adverse fetal outcomes. T2DM is preceded by prediabetes and shares similar pathophysiological complications. However, no studies have investigated the effects of maternal prediabetes on fetal HPA axis function and postnatal offspring development, hence this study. Pre-diabetic (PD) and non-pre-diabetic (NPD) female Sprague Dawley rats were mated with non-prediabetic males. After gestation, male pups born from the PD and NPD groups were collected. Markers of HPA axis function, adrenocorticotropin hormone (ACTH) and corticosterone were measured in all dams and pups. Glucose tolerance and expression of mineralocorticoid (MR) and glucocorticoid (GR) receptors were further measured in all pups at birth and their developmental milestones. The results demonstrated increased basal concentrations of ACTH and corticosterone in the dams from the PD group by comparison to NPD. Furthermore, the results show an increase in pups ACTH and corticosterone concentrations, impaired glucose tolerance and dysregulated MR and GR expression in the PD group at all developmental milestones. These observations reveal that pregestational prediabetes is associated with maternal dysregulation of the HPA axis, impacting offspring HPA axis development along with impaired glucose handling.