Thickness of the Supraspinatus and Biceps Tendons in Diabetic Patients

The effect of diabetes on tendons is not well known. There are some studies that analyze the impact of diabetes on tendon structures. It has been shown that chronic hyperglycemia causes some structural changes in tendon collagen (1,2). To the best of our knowledge, there is no published study on biceps and supraspinatus tendons. To observe the effect of diabetes on tendons, we studied the biceps and supraspinatus tendons because they can be easily measured by the ultrasonography (USG) technique. We measured both of these tendons using high resolution USG in 150 diabetic patients (50 type 1 and 100 type 2 diabetic patients, 75 men and 75 women, mean age 50.17 ± 15 years [±SD]) and 94 control outpatients (47 men and 47 women, mean age 47.53 ± 14 years) recruited from our clinic population.

All studies were performed and interpreted by a single radiologist using and Aloka SSD 620 ultrasound machine (Tokyo) with 7.5 MHz linear probe. The shoulder was examined by standard techniques (3). Maximal supraspinatus tendon thickness was measured on a longitudinal view, just in front of the lateral part of the humeral head (4). The long head of the biceps tendon was viewed in the bicipital groove, and its transverse thickness was measured (5).

Specifically, in diabetic patients, the thickness of the right biceps (RB) tendon was equal to 4 ± 1.05 mm, whereas it was 2.95 ± 0.38 mm in the control group (P < 0.0001). For the left biceps (LB) tendon, the thickness was 4.04 ± 1.02 mm in diabetic patients and 2.97 ± 0.26 mm in the control group (P < 0.0001). Similarly, the tendon thickness of the right supraspinatus (RS) and left supraspinatus (LS) was 6.60 ± 1.25 and 6.58 ± 1.18 mm in diabetic patients and 4.91 ± 0.41 and 4.96 ± 0.39 mm in the control group, respectively (P < 0.0001). The results of a logistic regression analysis indicated that the relative risk of a tendon increase in diabetic patients, as compared with the control group, was equal to 16.14 for the RB tendon, 60.66 for the LB tendon, 22.75 for the RS tendon, and 24.28 for the LS tendon.

Our results clearly indicated that there was a positive correlation between age and all four of the shoulder tendon thicknesses, i.e., P < 0.05 for RB and RS and P < 0.001 for LB and LS. On the other hand, we did not observe such a statistical relationship in the control group. Furthermore, there was only a positive correlation between the duration of diabetes and the thickness of both RS and LS, i.e., P < 0.05.

There are some similar studies on patients with amiloidosis (4). They found thickening of the rotator cuff due to the deposition of a β₂-microglobulin amiloidosis of the patients on chronic hemodialysis. In our study, none of the patients had a terminal kidney disease or had undergone hemodialysis treatment.

In summary, we observed an increase in biceps and supraspinatus tendon thickness in diabetic patients that was aggravated with aging in diabetic patients, although such a relationship did not exist for the control group. Our study is an important step in the direction of explaining this newly recognized complication of diabetes by using a noninvasive and relatively inexpensive USG technique, even though we need further studies to support our claim.