TITLE:
The Pancreas and Islets of Langerhans in Spaceflight—Current Evidence, Knowledge Gaps, and an Experimental Roadmap for Variable-Gravity Research
AUTHORS:
James Godwin
KEYWORDS:
Spaceflight, Microgravity, Pancreas, Islets of Langerhans, Beta-Cell, Insulin Resistance, HOMA-IR, Parabolic Flight, Partial Gravity, Diabetes, Organ-on-Chip
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.14 No.10,
October
15,
2026
ABSTRACT: Long-duration human spaceflight produces a metabolic environment characterised by skeletal-muscle unloading, altered energy balance, circadian disruption, stress signalling, and changes in liver, adipose, vascular, immune, and gastrointestinal physiology. These effects create a plausible demand for pancreatic compensation, yet the pancreas is one of the least directly studied organs in astronauts. This structured narrative review evaluates evidence concerning the endocrine and exocrine pancreas, with emphasis on the islets of Langerhans. Search strategy, inclusion and exclusion criteria, and an explicit five-tier scheme for classifying exposure type are stated in Section 2, and quantitative estimates are reported wherever the accessible record contains them. Human studies support the occurrence of inflight insulin resistance, but rest predominantly on a single fasting-derived index: in eight astronauts on approximately six-month missions, fasting glucose was essentially unchanged while fasting insulin rose by roughly half, so that the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) increased by close to sixty per cent. No human study has quantified beta-cell reserve, glucagon counter-regulation, pancreatic perfusion, morphology, fat content, or digestive function. Rodent spaceflight studies provide limited histological and molecular evidence of pancreatic remodelling, including islet-size differences that track mean body weight and are confounded by nutrition, housing, and hypokinesia, alongside organ-wide microRNA evidence implicating extracellular-matrix and developmental pathways in a fat-liver-pancreas axis, reported by its authors as a largely age-independent adaptation. In contrast, rotating culture systems and short real-microgravity experiments with isolated islets sometimes preserve viability, support three-dimensional organisation, improve insulin release, or induce delayed beta-cell cycle entry. These observations are not necessarily contradictory: low-shear culture may benefit isolated islets while systemic insulin resistance is expected to increase secretory demand on the intact pancreas. That second limb, however, remains a proposed mechanism rather than a measured astronaut response. The field is limited by sparse human phenotyping, small animal cohorts, platform confounding, weak separation of gravity from fluid-mechanical effects, incomplete quantitative reporting, and near-total neglect of alpha, delta, endothelial, neural, immune, and exocrine compartments. A tiered research programme is proposed, centred on counterbalanced variable-gravity parabolic flights using perfused human islet-on-chip systems, followed by sounding-rocket and orbital centrifuge experiments, multi-organ metabolic chips, and standardised longitudinal astronaut testing.