My shoulder has stiffened. Why are you asking about my blood sugar?

If you came in to talk about your shoulder and were asked when you last had a blood sugar test

Key points in 30 seconds

1. In an analysis that pooled 18 studies, people with diabetes were about 5 times more likely to develop frozen shoulder. About 1 in 7 or 8 people with diabetes had frozen shoulder.
2. Looked at the other way, about 3 in 10 people with frozen shoulder had diabetes. Some of them may have been living without knowing they had it.
3. A leading explanation is that when blood sugar stays high for a long time, tissues become stiff like a rubber band dipped in sugar water, and the shoulder capsule stiffens more easily too.
4. Frozen shoulder with diabetes tends to last longer, so we plan for a longer period and keep a record of the angles as we go.
5. If you get a shoulder injection, always tell them you have diabetes. Depending on the injection, blood sugar can rise for a while.

What we often hear

• "I came in for my shoulder. Why are you asking about my blood sugar?"
• "My diabetes is managed separately by my internal medicine doctor. Does it have anything to do with my shoulder?"
• "I can't remember when I last had a health checkup."
• "My shoulder seems to be loosening up much more slowly than other people's."

You came to a Korean medicine clinic because your shoulder hurts, and in the exam room you're asked:

"Do you happen to have diabetes? When did you last have your blood sugar checked?"

You came to talk about your shoulder, so why blood sugar? You may have been a little puzzled. Frozen shoulder and diabetes are much more closely linked than you might think. That's why this question matters, both for your shoulder and for your whole body beyond it.

With diabetes, frozen shoulder is about 5 times more likely

There's an analysis that pooled 18 studies on the link between frozen shoulder and diabetes.

• People with diabetes were about 5 times more likely to develop frozen shoulder than people without it.
• Among people with diabetes, the share who had frozen shoulder was about 13%, roughly 1 in 7 or 8.
• There was no clear difference between people who used insulin injections and those who took oral medication. This suggests the link is with diabetes itself, not with the type of treatment.

On top of that, frozen shoulder with diabetes is known to last longer and be more stubborn. Even with the same frozen shoulder, if diabetes is present, the expected course should be set differently from the start.

Why is that?

The cause isn't fully understood, but there's a leading explanation.

When blood sugar stays high for a long time, sugar sticks to the proteins that make up the body's tissues, and the tissues gradually become stiff and tough. It's like a rubber band dipped in sugar water: as it dries, it hardens and won't stretch well. The explanation is that the capsule around the shoulder joint is affected the same way, making it more likely to thicken and shrink.

The number to watch more closely is on the other side

In the same analysis, about 3 in 10 people with frozen shoulder had diabetes.

Some of them may have been living without knowing they had diabetes. They came to the hospital because of a stiff shoulder and learned about their blood sugar problem for the first time. That's why the researchers concluded that diabetes testing should be considered for patients who come in with frozen shoulder.

A stiff shoulder is a signal from your shoulder, but it may also be a signal from your whole body. If you look only at the shoulder, you may miss the bigger story.

That's why we ask in the exam room

If you already have diabetes, we ask how your blood sugar has been managed recently.

If you've never been diagnosed, we ask when you last had a blood test and whether anyone in your family has diabetes.

Because we base our care on blood tests, we check your blood sugar with a blood test when needed. If the numbers come back high, we guide you to an internal medicine doctor for diagnosis and management of diabetes. Treating the shoulder and managing blood sugar need to go hand in hand.

If you have diabetes, know these too

First, don't rush. If you start out knowing it may take a long time, you won't be discouraged or quit when things don't improve dramatically within a few weeks. Plan for a longer period, and in the meantime record your angles to see them slowly increase.

Second, the exercise principles are the same. Steadily, within a pain-free range. The rule "a pulling feeling is fine, stop at a stabbing pain" holds even if you have diabetes. Detailed moves are in the frozen shoulder exercise article.

Third, if you get a shoulder injection, always tell them you have diabetes. Depending on the type of injection, blood sugar can rise for a while, so whoever prescribes it needs to know.

Fourth, managing blood sugar is part of treating your shoulder. With the same treatment, your body responds under different conditions depending on whether your blood sugar is under control. Taking care of both your internal medicine care and your shoulder treatment is the fastest way forward.

How we work

First, we sort things out. We check whether it really is frozen shoulder, whether there's another cause such as a torn tendon, and which stage you're in. We also check for diabetes and your blood sugar status at this step. If needed, we look at the shoulder in partnership with the radiology clinic on the 2nd floor of the same building.

Second, we lower the pain and widen the range. The order, dealing with night pain first and then widening the stiff range, is the same as described in If shoulder pain wakes you up at night. If you have diabetes, we also look at your conditions for recovery using blood test and body composition (InBody) results, and if blood sugar management is needed, we guide you to see an internal medicine doctor as well.

Third, we check with angles. If you have diabetes, we set a slightly longer interval before re-measuring, but we record even small changes without missing any. If the angles don't improve within the set period, we don't keep repeating the same treatment. We reassess.

What changes

The discomfort of a stiff shoulder becomes a chance to take another look at your body. So your shoulder loosens up, and you also start managing blood sugar you didn't know about.

That's what we aim for.

The speed of recovery and the final range differ from person to person, depending on how severe the first symptoms were, how long you've had it, and your diabetes and blood sugar control.

Today's takeaway

If your shoulder has stiffened, check your blood sugar too. Frozen shoulder and diabetes can be signals that point to each other.

There's just one thing to do today. Find out when you last had a blood test (including blood sugar). If you have your health checkup results, look for the blood sugar line, and if you already have diabetes, write down your recent numbers.

If your shoulder has stiffened and it's been more than a year since your last blood sugar test, you're welcome to bring your results with you, or get tested first. We're open until 8:30 p.m. on weekdays, and on weekends and public holidays too.

The course of frozen shoulder and the evidence for treatment are summarized in the director's column I heard frozen shoulder gets better if you just leave it.

For questions or appointments, message us in English through the messenger at the bottom right of the page, or call +82-53-716-1175.

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References

Zreik NH, Malik RA, Charalambous CP. Adhesive capsulitis of the shoulder and diabetes: a meta-analysis of prevalence. Muscles Ligaments Tendons J. 2016;6(1):26-34. doi:10.11138/mltj/2016.6.1.026. PMID: 27331029