People who have diabetes more often affected by trigger finger: Study

People with diabetes are more likely than the general population to suffer from trigger finger or locked fingers. A study done by Lund University in Sweden found that when blood sugar levels are high, the risk of getting affected increases.

The study’s findings were published in the journal Diabetes Care. Trigger finger occurs when one or more fingers, most commonly the ring finger or thumb, become bent and difficult to straighten. The thickening of the tendons that bend the finger and their connective tissue sheath causes the finger to become stuck in a bent posture towards the palm. It is a painful ailment that is generally managed with cortisone injections but occasionally necessitates surgery.

“At the hand surgery clinic, we have noted for a long time that people with diabetes, both type 1 and type 2, are more often affected by trigger finger. Over 20 percent of those who require surgery for this condition are patients who have, or will develop, diabetes,” says Mattias Rydberg, doctoral student at Lund University, resident physician at Skane University Hospital and first author of the study.

The researchers investigated two registers to see if high blood sugar (blood sugar dysregulation) increased the incidence of trigger finger. The first was Region Skane’s healthcare database, which included all diagnoses, and the second was the Swedish national diabetes register. Trigger finger affects between 1% and 1.5% of the population, although the diagnosis occurs in 10-15% of individuals with diabetes, and the occurrence is most common in type 1 diabetic patients.

The newly published study strengthens the pattern of blood sugar being a crucial factor for an increased risk of being affected by trigger finger. High blood sugar increased the risk of being affected by trigger finger among both men and women in the groups with type 1 diabetes and type 2 diabetes.

Blood sugar is measured in HbA1C, also referred to as long-term blood sugar, and when regulated, is under 48. The group of men with the worst regulated blood sugar (HbA1C > 64) had up to 5 times as high a risk of being affected than men with well-regulated (HbA1< 48) blood sugar.

“However, we can’t know for certain if any of the groups seek healthcare more often than others which could be a factor that affects the results,” says Mattias Rydberg.

The mechanism, or mechanisms, behind the increased risk are unknown, but there are theories that high blood sugar makes both the flexor tendons and their connective tissue sheaths thicker, thus causing them to lock more easily. It was previously known that those with unregulated blood sugar are more prone to nerve entrapments in the hand.

“It is important to draw attention to the complications from diabetes and how they can arise in order to discover them early, which enables faster treatment and thus a better outcome. In addition to nerve compressions and trigger finger, there may also be a link with thickening of the connective tissue in the palm (Dupuytren’s contracture), impairment of joint movement and the risk of arthritis at the base of the thumb,” says Lars B. Dahlin, professor at Lund University and consultant in hand surgery at Skane University Hospital.

“The mechanisms behind these complications probably differ in the case of diabetes. The results of this study are interesting, as we can show that blood sugar dysregulation has a connection with the development of trigger finger,” he added.

The next step in the research will be to chart how effective it is to operate on patients with diabetes who are affected by trigger finger.

“From our experience at the clinic, surgery goes well and there are few complications, but it takes a little longer for patients with type 1 and type 2 diabetes to regain full movement and function. We want to investigate this hypothesis further.

Another interesting idea is to see if trigger finger could be a warning signal for type 2 diabetes. It is far from all who are affected by trigger finger that have diabetes, but it would be interesting to see if by using modern registers we can discover those who are in the risk zone for developing diabetes,” concludes Mattias Rydberg.

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