Mitochondrial Dysfunction: Linking Type 1 Diabetes and Sarcopenia

An update on bone in diabetes

PURPOSE OF REVIEW

As the prevalence of diabetes mellitus (DM) increases due to urbanization, aging populations, and lifestyle changes, it is crucial to understand the mechanisms, diagnosis, and treatment of diabetes-related bone disorders. This review highlights recent advancements in the field and explores their implications for clinical practice and research.

RECENT FINDINGS

Recent studies have elucidated the complex interplay between diabetes and bone health, emphasizing the roles of advanced glycation end-products (AGEs), inflammation, oxidative stress, senescence, and molecular signaling pathways such as Wnt, mammalian target of rapamycin (mTOR), and exosome-mediated mechanisms. Key findings highlight the significance of bone marrow adipose tissue (BMAT) in bone metabolism and the impact of sarcopenia on fracture risk. Novel diagnostic tools, including miRNA biomarkers and emerging therapeutic strategies like exosome-based therapies and glycogen synthase kinase 3 beta (GSK3β) inhibitors, offer promising opportunities for improving bone health in diabetic patients.

SUMMARY

The findings underscore the need for integrated strategies for managing diabetes-related bone complications. Clinicians should prioritize early screening, lifestyle interventions, and personalized pharmacological treatments to mitigate fracture risk and improve bone health in diabetic patients. Future research should focus on optimizing diagnostic tools and developing targeted therapies to address the unique challenges of bone disorders related to diabetes.

Texture analysis of T1- and T2-weighted images identifies myofiber atrophy and grip strength decline in streptozotocin-induced type 1 diabetic sarcopenia rats

BACKGROUND

Type 1 diabetes mellitus is associated with accelerated skeletal muscle aging and sarcopenia, a condition characterized by muscle mass and function loss. Early and noninvasive evaluation of muscle microstructural damage is critical for managing sarcopenia in diabetes. This study evaluated the potential of MRI texture analysis as a noninvasive imaging tool to assess myofiber size and grip strength alterations in a rat model of diabetic sarcopenia.

MATERIALS AND METHODS

Twenty SD rats were randomly and evenly allocated to the control (CON) and diabetic sarcopenia (DS) groups. Blood glucose, body weight, and forelimb grip strength were measured weekly. In the eighth week, axial T1WI and T2WI scans were performed to extract 16 texture features of the gastrocnemius muscle. The size of the fibers, including the cross-sectional area, perimeter, and minFeretDiam, was calculated from the HE-stained images. Differences between the two groups were analyzed via t tests or Mann‒Whitney U tests. Receiver operating characteristic (ROC) analysis was conducted to evaluate the diagnostic performance of MRI texture features. Associations between MRI texture features, grip strength, and myofiber size were assessed via Spearman correlation analysis.

RESULTS

The DS group presented significant reductions in body weight, grip strength, and myofiber size (p < 0.001). Seven texture features demonstrated high repeatability. Among them, T1WI_Entropy and T2WI_Entropy were significantly lower, whereas T1WI_Mean, T2WI_Mean, and T2WI_Variance were greater in the DS group than in the control group (p < 0.05 to p < 0.001). ROC analysis revealed that the MRI texture features performed well in differentiating the DS and CON groups (AUC 0.830 ~ 1.000). Strong correlations were found between MRI texture parameters and muscle strength and myofiber size.

CONCLUSION

Muscle texture analysis based on T1WI and T2WI effectively differentiated type 1 diabetic sarcopenic rats from normal controls and revealed strong associations with muscle strength and myofiber size. These findings indicate that MRI texture parameters serve as potential biomarkers for diagnosing muscle damage in type 1 diabetic sarcopenia patients, suggesting that MRI texture parameters are promising noninvasive tools for early detection and monitoring of myofiber atrophy in diabetic sarcopenia.

Mitochondrial dysfunction and beneficial effects of mitochondria-targeted small peptide SS-31 in Diabetes Mellitus and Alzheimer's disease

Diabetes and Alzheimer's disease are common chronic illnesses in the United States and lack clearly demonstrated therapeutics. Mitochondria, the "powerhouse of the cell", is involved in the homeostatic regulation of glucose, energy, and reduction/oxidation reactions. The mitochondria has been associated with the etiology of metabolic and neurological disorders through a dysfunction of regulation of reactive oxygen species. Mitochondria-targeted chemicals, such as the Szeto-Schiller-31 peptide, have advanced therapeutic potential through the inhibition of oxidative stress and the restoration of normal mitochondrial function as compared to traditional antioxidants, such as vitamin E. In this article, we summarize the pathophysiological relevance of the mitochondria and the beneficial effects of Szeto-Schiller-31 peptide in the treatment of Diabetes and Alzheimer's disease.

Impaired Function and Altered Morphology in the Skeletal Muscles of Adult Men and Women With Type 1 Diabetes

CONTEXT

Previous investigations on skeletal muscle health in type 1 diabetes (T1D) have generally focused on later stages of disease progression where comorbidities are present and are posited as a primary mechanism of muscle dysfunction.

OBJECTIVE

To investigate skeletal muscle function and morphology across the adult lifespan in those with and without T1D.

DESIGN

Participants underwent maximal contraction (MVC) testing, resting muscle biopsy, and venous blood sampling.

SETTING

Procedures in this study were undertaken at the McMaster University Medical Centre.

PARTICIPANTS

Sixty-five healthy adult (18-78 years old) men/males and women/females (T1D = 34; control = 31) matched for age/biological sex/body mass index; self-reported physical activity levels were included.

MAIN OUTCOME MEASURES

Our primary measure in this study was MVC, with supporting histological/immunofluorescent measures.

RESULTS

After 35 years of age ("older adults"), MVC declined quicker in T1D subjects compared to controls. Loss of strength in T1D was accompanied by morphological changes associated with accelerated aging. Type 1 myofiber grouping was higher in T1D, and the groups were larger and more numerous than in controls. Older T1D females exhibited more myofibers expressing multiple myosin heavy chain isoforms (hybrid fibers) than controls, another feature of accelerated aging. Conversely, T1D males exhibited a shift toward type 2 fibers, with less evidence of myofiber grouping or hybrid fibers.

CONCLUSIONS

These data suggest impairments to skeletal muscle function and morphology exist in T1D. The decline in strength with T1D is accelerated after 35 years of age and may be responsible for the earlier onset of frailty, which characterizes those with diabetes.

Exercise Training and Neuromuscular Parameters in Patients With Type 1 Diabetes: Systematic Review and Meta-Analysis

BACKGROUND

The present study aimed to systematically review the literature on the effects of physical training on neuromuscular parameters in patients with type 1 diabetes mellitus (T1DM).

METHODS

The PubMed, Scopus, EMBASE, and COCHRANE databases were accessed in September 2020. Clinical trials that evaluated the effects of physical training on neuromuscular parameters (maximum strength, resistance strength, muscle power, muscle quality, and muscle thickness) of patients with T1DM compared with a control group were considered eligible. The results were presented as the standardized mean difference with 95% confidence intervals. Effect size (ES) calculations were performed using the fixed effect method, with α = .05.

RESULTS

Combined training increased the maximum strength levels in individuals with T1DM to a lesser extent than in healthy individuals (ES: 0.363; P = .038). Strength training increased the maximum strength (ES: 1.067; P < .001), as well as combined training (ES: 0.943; P < .001); both compared with aerobic training in patients with T1DM. Strength training increased the maximum strength in a similar magnitude to combined training in patients with T1DM (ES: -0.114; P = .624).

CONCLUSION

Both combined training and strength training represent effective strategies for improving the maximum strength in individuals with T1DM.