Trigger finger, medically known as stenosing tenosynovitis, is a common condition affecting the hand that restricts normal finger movement. It involves inflammation and thickening within the tendons or their protective sheaths, causing the finger to catch or lock when bent. While it occurs in the general population, its prevalence is significantly higher in individuals with diabetes, affecting up to 10% of the diabetic population compared to 2% to 3% of the general population. This strong, specific link means that diabetes fundamentally alters the tissues in the hand, making the development of this condition far more likely.
Anatomy of Stenosing Tenosynovitis
Normal finger movement relies on long, cord-like structures called flexor tendons, which connect the muscles in the forearm to the bones in the fingers. These tendons glide smoothly through a series of tissue tunnels known as the flexor tendon sheath. Along this sheath are bands of tissue called annular pulleys, which act like the eyes of a fishing rod, holding the tendons close to the finger bones.
The A1 pulley, located at the base of the finger where it meets the palm, is the structure most commonly involved in trigger finger. When the tendon or its sheath becomes inflamed and thickened, the space for the tendon to move freely is narrowed. The resulting friction causes irritation, making it difficult for the tendon to pass through the constricted A1 pulley.
How Diabetes Directly Causes Tendon Thickening
The core mechanism linking diabetes to trigger finger is chronic high blood glucose, or hyperglycemia. Over time, elevated glucose levels drive a non-enzymatic reaction between sugar molecules and proteins, particularly collagen, which is abundant in tendons and the A1 pulley. This process leads to the formation of compounds called Advanced Glycation End products (AGEs).
AGEs accumulate in tissues with a slow turnover rate, such as the collagen found in the tendon sheath. The formation of these AGEs creates pathological cross-links between the collagen fibers. These cross-links essentially “glue” the fibers together, resulting in a tendon and pulley system that is thicker, stiffer, and less elastic than normal tissue.
The reduced flexibility and increased bulk of the tendon sheath and A1 pulley directly narrow the passageway for the flexor tendon. This structural change creates the physical environment for impingement, long before any mechanical stress or inflammation occurs. The increased collagen build-up impairs the natural degradation and repair of the tendon tissue.
Recognizing the Signs and Who Is Most Susceptible
Trigger finger often begins with tenderness and pain felt in the palm, directly over the A1 pulley at the base of the affected finger. Stiffness, particularly noticeable in the morning, is one of the earliest symptoms a person may experience. As the condition progresses, a distinct clicking, popping, or snapping sound may be felt when bending or straightening the finger.
In more advanced stages, the finger may become momentarily stuck or locked in a bent position, requiring the use of the other hand to manually straighten it. Diabetic patients are also more likely to experience trigger finger in both hands (bilateral presentation) and in multiple fingers simultaneously, reflecting the systemic nature of the underlying disease. The condition is also often seen alongside other hand complications related to diabetes, such as carpal tunnel syndrome.
The highest risk factors specific to the diabetic population are the duration of the disease and the degree of blood sugar control. High long-term blood sugar levels, measured by HbA1c, are strongly associated with an increased risk of developing the condition. Older adults and those with a longer history of diabetes are the most susceptible.
Managing Trigger Finger with Underlying Diabetes
Initial treatment for trigger finger typically involves non-surgical approaches like rest, splinting the finger to keep it straight, and taking oral anti-inflammatory medications. Physical therapy, including gentle stretching exercises, can also be used to help improve finger flexibility and range of motion.
For many people, the next step is a corticosteroid injection into the tendon sheath to reduce inflammation. In diabetic patients, these injections require careful consideration because the steroid medication can temporarily elevate blood sugar levels. This hyperglycemic effect may last for at least five days, requiring patients to monitor their glucose levels vigilantly and potentially adjust their diabetes medication under a doctor’s guidance. The effectiveness of these injections is also often lower in people with diabetes compared to the general population.
If non-surgical treatments fail, surgical release of the A1 pulley is an option that provides a high success rate. The procedure involves cutting the A1 pulley to create more space for the tendon to glide freely. Individuals with diabetes may face a slightly higher risk of post-operative complications and experience slower wound healing due to impaired circulation and poor glucose control. Maintaining strict blood sugar control before and after surgery is important for a successful recovery.