Space Flight-Promoted Insulin Resistance as a Possible Disruptor of Wound Healing.

During space flight, especially when prolonged, exposure to microgravity results in a number of pathophysiological changes such as bone loss, muscle atrophy, cardiovascular and metabolic changes and impaired wound healing, among others. Interestingly, chronic low-grade inflammation and insulin resistance appear to be pivotal events linking many of them. Interestingly, real and experimental microgravity is also associated to altered wound repair, a process that is becoming increasingly important in view of prolonged space flights. The association of insulin resistance and wound healing impairment may be hypothesized from some dysmetabolic conditions, like the metabolic syndrome, type 2 diabetes mellitus and abdominal/visceral obesity, where derangement of glucose and lipid metabolism, greater low-grade inflammation, altered adipokine secretion and adipocyte dysfunction converge to produce systemic effects that also negatively involve wound healing. Indeed, wound healing impairment after traumatic events and surgery in space remains a relevant concern for space agencies. Further studies are required to clarify the molecular connection between insulin resistance and wound healing during space flight, addressing the ability of physical, endocrine/metabolic, and pharmacological countermeasures, as well as nutritional strategies to prevent long-term detrimental effects on tissue repair linked to insulin resistance. Based on these considerations, this paper discusses the pathophysiological links between microgravity-associated insulin resistance and impaired wound healing.

The gut microbiome as possible mediator of the beneficial effects of very low calorie ketogenic diet on type 2 diabetes and obesity: a narrative review.

Several studies have shown a strong correlation between the different types of diets and gut microbiota composition on glycemia and weight loss. In this direction, low-carbohydrate and ketogenic diets have gained popularity, despite studies published so far leading to controversial results on subjects with diabetes. In this narrative review, firstly, we aimed to analyze the role of very-low-calorie ketogenic diets (VLCKDs) in type 2 diabetes (T2DM) and obesity management. Secondly, in this context, we focused attention on gut microbiota as a function of VLCKD, particularly in T2DM and obesity treatment. Finally, we reported all this evidence to underline the importance of gut microbiota to exalt new nutritional strategies for "tailor-made" management, treatment, and rehabilitation in subjects with T2DM and obesity, even with diabetic complications. In conclusion, this narrative review outlined the beneficial impact of VLCKD on gut microbiota even in subjects with T2DM and obesity, and, despite inner VLCKD short-duration feature allowing no sound-enough provisions for long-term outcomes, witnessed in favor of the short-term safety of VLCKD in those patients.Level of evidence Level V: Opinions of authorities, based on descriptive studies, narrative reviews, clinical experience, or reports of expert committees.