Ultraviolet (UV) rays

Sunlight contains ultraviolet (UV) rays that are strongest in the spring and summer. Two types of UV (UVA and UVB) can damage the skin: 

1. Ultraviolet A (UVA)

  • These are long rays.
  • They penetrate deeply into the skin (dermis) and cause premature aging and wrinkles.
  • They also play a role in the appearance of certain types of skin cancers.

2. Ultraviolet B (UVB)

  1. UVB rays are short but 1,000 times more powerful than UVA.
  2. They alter skin cells and cause sunburn.
  3. They are responsible for most skin cancers and cataracts.

The importance of protection from UV rays for a person with diabetes

  • People with diabetes who suffer from neuropathy might not feel the burning sensation caused by sun exposure.
  • Some medications can cause increased sensitivity to the sun.
  • The warming of the skin by the sun activates blood circulation, which can accelerate the absorption of insulin. The risk of hypoglycemia is therefore increased if an injection site is exposed to the sun. For this reason, it is advisable to choose an injection site not exposed to the sun and measure your blood glucose more often.
  • Prolonged exposure to sunlight can damage the structures of the eye. A person with diabetes needs to be extra careful because damage can occur without any sensation of symptoms. The healing process is also longer.
  • Over the long term, UV absorption can contribute to the appearance of cataracts. Chemical changes within the crystalline lens of people with diabetes may amplify this problem. According to the World Health Organization (WHO) (2016), 20% of cataracts are caused by eye exposure to UV rays. 


The UV weather index 

To find out how intense the sun’s UV rays are at any given time, check the UV index included with your local weather forecast. The UV index varies throughout the day, reaching its maximum value around noon (when the sun is highest in the sky) and its lowest value in the early morning or late afternoon.

  • An index of 0 to 2 is considered low. Minimal protection is sufficient if you spend less than one hour outdoors.
  • An index of 3 to 5 (moderate) requires a hat, sunglasses and the application of sunscreen if you plan to spend more than 30 minutes outdoors.
  • An index of 6 to 7 is considered high. Protection (hat, sunglasses and sunscreen) is therefore required. You should also reduce your exposure to the sun between 11 a.m. and 4 p.m. and stay in the shade. The same applies for an index of 8 to 10 (very high).


  • Be sure to use enough. If you are of average height, you should apply 2 mg of sunscreen per cm2 of skin, or about 30 ml (2 tablespoons) per application.
  • If you use spray sunscreen, be sure to spread it with your hand after you’ve sprayed it on to ensure that you’ve covered all exposed areas. 
  • Don’t forget to apply sunscreen to your ears, neck and to your feet if wearing sandals.
  • Reapply sunscreen every two hours. 
  • Apply a waterproof sunscreen 30 minutes before swimming. Always apply sunscreen before applying makeup or insect repellant. 
  • Also apply lip balm with a sun protection factor (SPF) of 15. Reapply as needed.

Criteria to help you choose the right sunscreen:

  • Protection from both UVB (responsible for sunburn) and UVA (associated with premature aging of the skin). Look for the words “broad spectrum,” whether in a cream, lotion, gel or spray.
  • Ingredients should be “micronized” or “non-nano” (no nanoparticles).
  • Product should carry the seal of the Canadian Dermatology Association. 
  • Minimum 30 sun protection factor (SPF).
  • Sunscreen lets you prolong your sun exposure but is only one more way to protect yourself from the sun.

What does SPF mean?

Not all sunscreens offer the same protection. The sun protection factor (SPF) is a number that refers to the product’s ability to filter or block ultraviolet B (UVB) rays. Sunscreens on the market have an SPF ranging from 2 to 100 but NONE offer total protection. Their effectiveness depends on the amount used, skin type, duration of exposure and the intensity of the sunlight. 

  • An SPF of 15 blocks 93% of UVB rays; 
  • An SPF of 30 or higher blocks 97% of UVB rays but is not twice as effective as an SPF of 15.

Clothing and hats

  • Cover the skin with clothing to protect it from UV rays.
  • Loose, tightly woven clothing provides the best protection. If you can see light through the garment, UV rays can also pass through.
  • Dark-colored fabrics provide greater protection from UV rays than light-coloured fabrics.
  • It is important to wear a hat to protect your scalp and face.

Certain clothing has been designed specifically for UV protection. Its label carries a UV protection code (UPF). A higher UPF means better protection. Such clothing is ideal if you regularly spend a great deal of time in the sun.


  • Choose sunglasses offering protection from UVA and UVB and that mention UV400. 
  • Dark or very dark sunglasses (tinted grey, brown or green) are recommended 
  • Polarized sun lenses cut glare and are ideal for outdoor activities in snow or on water. 
  • The frames should be wide or wraparound to protect the delicate skin around the eyes.