GREATER exposure to sunlight may be associated with lower blood glucose levels and a reduced risk of Type 2 diabetes, according to a large UK study.\u00a0<\/p>\n
Researchers analysing data from more than 400,000 UK Biobank participants found that short-term sunlight exposure was associated with modest reductions in blood glucose, while a measure of longer-term sun exposure was linked to a lower likelihood of Type 2 diabetes.\u00a0<\/p>\n
Sunlight and Blood Glucose\u00a0<\/p>\n
The researchers examined data from 429,368 UK Biobank participants, comparing blood glucose measurements with levels of ultraviolet A (UVA) radiation around participants\u2019 homes during the two and seven days before their assessment.\u00a0<\/p>\n
Sunlight exposure was estimated using satellite data, while the analysis accounted for factors including temperature, season, day of the week, and longer-term trends.\u00a0<\/p>\n
It was found that during winter, each 1 W\/m\u00b2 increase in average UVA exposure over the previous two days was associated with a 0.015 mmol\/L reduction in blood glucose.\u00a0For seven-day exposure, glucose was 0.027 mmol\/L lower for each 1 W\/m\u00b2 increase. A smaller association was also\u00a0observed\u00a0during spring.\u00a0<\/p>\n
The relationship, however,\u00a0was not linear.\u00a0Researchers found that glucose levels fell most sharply when sunlight exposure increased from\u00a0very low\u00a0levels, before reaching a plateau at higher exposure. This could help explain why the strongest associations were seen during winter, when overall sunlight levels are lower.\u00a0<\/p>\n
Lower Diabetes Risk with Greater Sun Exposure\u00a0<\/p>\n
The study\u00a0also investigated longer-term exposure using reported\u00a0sun-bed\u00a0use as an indicator of habitual sun exposure.\u00a0<\/p>\n
Among 408,531 participants, 16,971 had been diagnosed with diabetes. After adjusting for factors including BMI, smoking, physical activity, education, employment, deprivation, and mental health, occasional\u00a0sun-bed\u00a0users\u00a0were found to have\u00a0a 14% lower hazard of Type 2 diabetes compared with non-users.\u00a0\u00a0<\/p>\n
Frequent users had an even lower hazard at\u00a022%.\u00a0Frequent users also had higher vitamin D levels and slightly lower BMI and blood glucose levels,\u00a0<\/p>\n
However, the researchers emphasised that these results should not be interpreted as evidence supporting sunbed use, which carries established health risks\u00a0including increasing the risk of dangerous skin cancers like melanoma.\u00a0\u00a0\u00a0<\/p>\n
Instead, sunbed use may be a marker of greater overall sunlight exposure, as people who use sunbeds may also be more likely to seek out the sun regularly.\u00a0<\/p>\n
Beyond Vitamin D\u00a0<\/p>\n
The findings raise the possibility that sunlight could influence metabolic health through mechanisms beyond vitamin D.\u00a0<\/p>\n
The authors highlighted nitric oxide, which is released from stores in the skin following UV exposure and may improve blood flow, insulin secretion, and insulin sensitivity. Red and near-infrared wavelengths in sunlight may also affect mitochondrial energy production.\u00a0<\/p>\n
Importantly, the study was observational and cannot\u00a0establish\u00a0that sunlight directly prevents Type 2 diabetes. Ambient UVA was also used as a proxy for personal sunlight exposure, meaning researchers could not\u00a0determine\u00a0how much time individual participants\u00a0actually spent\u00a0outdoors.\u00a0<\/p>\n
The authors conclude that clinical studies are now needed to investigate the mechanisms involved and\u00a0determine\u00a0whether there are safe,\u00a0optimal\u00a0levels of sunlight exposure that could support metabolic health.\u00a0<\/p>\n
Reference\u00a0<\/p>\n