Exposure to artificial lighting at night: from an ecological challenge to a risk factor for glucose dysmetabolism and gestational diabetes? Narrative review.

Introduction: Artificial lighting at night (ALAN) leads to pervasive light pollution, affecting ecosystems and human health globally. Satellite assessments reveal widespread nocturnal illumination worldwide and research indicates adverse health effects. Environmental light pollution disrupts natural cycles, affecting the behavior and reproduction of various organisms.

Aim/method: In this narrative review we aimed to present research on the effects of ALAN on glucose metabolism and diabetes and hone on its recently reported association with gestational diabetes (GDM).

Results: Conflicting data exist on the effects of melatonin's administration vis-à-vis glycemia, with some studies suggesting beneficial outcomes for patients with type 2 diabetes mellitus and insomnia. Ambient light influences plasma glucose, with bright light increasing both fasting and postprandial glucose levels. Perinatal light exposure is linked to later-life health risks and prenatal exposure to ALAN is linked to fetal macrosomia. Analyzing European ALAN data in conjunction with epidemiological records for GDM reveals a notable probable association. Additionally, recent research from China (one case-control and two cohort studies) has shown that exposure to ALAN during pregnancy significantly increases the risk of GDM.

Discussion/conclusion: Despite progress, interdisciplinary research is needed to understand the impact of light pollution on health, especially regarding disrupted light-dark cycles and physiological functions relevant to conditions like GDM. At present, the simplest advice for all people and particularly for women who anticipate pregnancy, or for pregnant women, is to ensure a totally dark environment during sleep time.