Locked fingers, known as ‘trigger finger’, are more common among people with diabetes than in the general population, finds a study published in Diabetes Care. A study led by Lund University in Sweden shows that the risk of being affected increases with hyperglycaemia.
Trigger finger means that one or more fingers, often the ring finger or thumb, ends up in a bent position that is difficult to straighten out. It is due to the thickening of tendons, which bend the finger, and their connective tissue sheath, which means that the finger becomes fixed in a bent position towards the palm. It is a painful condition that can often be treated with cortisone injections, but sometimes requires 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 Skåne University Hospital and first author of the study.
To study whether blood sugar dysregulation increases the risk of trigger finger, the researchers examined two registers. The prevalence of trigger finger in the general population 1–1.5%, but is 10-15% among those who have diabetes, particularly in type 1 diabetes.
The study added to the evidence for a link between blood sugar and trigger finger. Hyperglycaemia 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. 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 (HbA1c < 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,” said 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. 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,” said Lars B. Dahlin, professor at Lund University and consultant in hand surgery at Skåne University Hospital.
Future research will measure the effectiveness of operating 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,” concluded Mattias Rydberg.
Source: Lund University
