High A1c Raises Trigger Finger Risk in Both Diabetes Types

Miriam E. Tucker

October 27, 2022

High A1c levels are associated with the development of "trigger finger" in people with type 1 and type 2 diabetes, researchers find.

Trigger finger, officially called stenosing flexor tenosynovitis, is a common disorder affecting both the flexor tendons and tight pulleys surrounding them, causing the fingers to lock in flexion and to snap, ie "trigger," when manually pulled back. The likely cause is a combination of tendinopathy and pulley thickening.

Diabetes is a known risk factor developing trigger finger, but this new study, based on two Swedish population databases, is the largest thus far to explore the relationship. It's also the first to examine the two diabetes types separately and by gender.  

The findings suggest that the "optimal treatment of diabetes seems to be of importance for prevention of diabetic hand complications, such as trigger finger," write Mattias Rydberg, MD, a resident in hand surgery and PhD student at Lund University, Sweden, and colleagues. The findings have been published in Diabetes Care.

In a prior study published earlier in 2022 based on the same Swedish datasets, Rydberg and colleagues found that the "diabetic hand" phenomenon includes the previously recognized trigger finger and Dupuytren's disease, as well as carpal tunnel syndrome, ulnar nerve entrapment, and possibly osteoarthritis of the first carpometacarpal joint — all conditions more common in people with either diabetes type, particularly type 1 diabetes, than those without diabetes.  

"As a hand surgeon, I think clinicians should always screen for hand problems in people with diabetes. It's an easy question: 'Are you having problems with your hands?' It's an open question and you can ask it in 2 seconds. Of course, the heart, eye, and kidney problems are more important. But fingers getting stuck, and not being able to use your hand is also quite disturbing," Rydberg told Medscape Medical News.

The link between diabetes and trigger finger is likely caused by a combination of oxidative stress due to diabetes-induced hypoxia, intracellular hyperosmotic proteins causing edema, and formation of advanced glycation end products resulting from prolonged hyperglycemia. "When you operate you can see within the tendons...They're inflamed, and everything is a bit swollen, especially in type 1 diabetes," Rydberg said.

Trigger finger is treatable with corticosteroid injections or surgical open release of the A1 pulley. The injections — which often dramatically raise blood glucose levels temporarily — also aren't always a permanent treatment, especially in people who have had diabetes for a long time or who have multiple trigger fingers. "It's more likely to recur [following injections] in those individuals. I'm not sure if the data support that, but it's my clinical experience," Rydberg said, noting that he nonetheless offers both to patients.

People with diabetes tend to recover from the trigger release surgery a bit more slowly than those without diabetes, and may experience more pain and stiffness in the fingers, but after a year there are no differences. "So you can tell your patients with diabetes it might take some time but you will recover," he told Medscape Medical News.

Direct Relationship With Trigger Finger, A1c

The study population included 9682 adults with type 1 diabetes and 85,755 with type 2 diabetes from the Swedish National Diabetes Register from 2004-2019. Those data were cross-linked to those of the Region Skåne's healthcare database, which includes all diagnoses for 1.1 million adults. Over the study period, 486 women and 271 men with type 1 diabetes and 1143 women and 1009 men with type 2 diabetes were diagnosed with trigger finger.  

Among those with type 1 or type 2 diabetes, mean A1c was higher for both men and women diagnosed with trigger finger during the study period compared with those who weren't (all P < .01).

Both men and women diagnosed with trigger finger had a longer duration of diabetes for both type 1 and type 2 diabetes (both P < .01). The associations were significant both with A1c as a continuous variable and when divided into tertiles by mean A1c, even after adjustment for confounders such as age, smoking, diabetes duration, body mass index, and blood pressure.

The greatest risk for trigger finger was found in men with type 1 diabetes who had A1c levels > 64 mmol/mol (8%), with an odds ratio 5.33 (P < .001) compared with men with type 1 diabetes who had A1c levels ≤ 48 mmol/mol (6.5%).

Rydberg is planning to investigate the predictive value of trigger finger for metabolic syndrome and type 2 diabetes, aiming to identify which specific populations might benefit from diabetes screening. He is also examining various aspects of the other diabetes-related hand complications, including carpal tunnel syndrome and ulnar nerve entrapment. At the same time, he's writing his PhD thesis entitled, "The diabetic hand."

Rydberg has reported no relevant financial relationships.

Diabetes Care. Published online August 25, 2022. Full text

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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