The connection between blue eyes and type 1 diabetes stems from the findings of a 2011 study published in Diabetes/Metabolism Research and Reviews. The study team examined the iris color of more than 280 Caucasian individuals within two specific areas of Italy who were diagnosed with type 1 diabetes. To compare, the researchers also looked at the iris color of nearly 300 participants who did not have the condition. It was found that having blue eyes proved to be a significant risk factor for developing type 1 diabetes.

Affecting approximately 5% to 10% of diabetes patients, the U.S. Centers for Disease Control and Prevention (CDC) explains that type 1 diabetes is an autoimmune condition in which the body self-attacks the pancreas and prevents the organ from producing adequate amounts of insulin. As a result, the body is unable to convert blood sugar into energy. Normally, insulin achieves this by facilitating the entry of blood sugar into our cells, but with nowhere to go, blood sugar accumulates in the blood. Mayo Clinic experts state that this can lead to excessive hunger or thirst, weakness, weight loss, increased urination, blurred vision, and more.