“First of all, thyroid dysfunction and type 2 diabetes are the two most common causes or common diseases in endocrinology. Now thyroid hormone is very important for our metabolism—the way that our body handles energy—and it's, therefore, also important in control of weight and cholesterol metabolism. That's why we hypothesize that it could also be important in development of diabetes type 2,” Dr. Chaker stated.
The study investigated the association of thyroid function to incident prediabetes, incident diabetes and progression from prediabetes to diabetes. There were 8,452 study participants (Rotterdam Study), all diabetes-free at baseline, average age of 65-years, and 58% were female. All study participants underwent blood tests to measure glucose, thyroid stimulating hormone (TSH) and free thyroxine (FT4). Glucose below 6 was considered normal; prediabetes was defined as a fasting glucose between 6 and 7; and diabetes was defined as a fasting glucose above 7. TSH and FT4 were the primary laboratory markers, which were normal on average. Participants were re-examined every 2 to 3 years for development of type 2 diabetes.
Low thyroid function (hypothyroidism) represented by higher TSH is associated with a 1.2-fold increased risk of diabetes and a 1.4-fold increased risk of progression from prediabetes to diabetes. During the mean follow-up period of 7.9 years, 1100 participants developed prediabetes and 798 developed diabetes. Dr. Chaker stated, “If you take lifetime risk into account, these numbers would be larger, as we know that people with prediabetes, about 70-75% over a lifetime develop diabetes.”
Chaker L, Ligthart S, Korevaar TIM, et al. OR33-2: Thyroid Function and Type 2 Diabetes Risk: A Population-Based Prospective Cohort Study. The Endocrine Society’s 98th Annual Meeting & Expo, Boston Convention and Exhibition Center, Boston, MA. April 3, 2016.