People with diabetes are much more prone to develop problems with tendons than normal people. This is probably because the blood supply to tendons is normally pretty sparse, so very early diabetic changes in blood vessels may show up first in tendons.
Another possible explanation may be that high blood sugars may cause abnormal thickening of tendons. This was demonstrated in a study published in the journal, Diabetes Care
.Thickness of the Supraspinatus and Biceps Tendons in Diabetic Patients
Mujde Akturk et al. Diabetes Care
Some common forms of tendon damage that are more common in people with diabetes and pre-diabetes are carpal tunnel syndrome, tarsal tendon syndrome (a form of carpal tunnel that strikes the feet) and frozen shoulder. Carpal Tunnel May Predict Diabetes (WebMD)Some Long-Term Sequelae of Poorly Controlled Diabetes that are Frequently Undiagnosed, Misdiagnosed or Mistreated.
Richard K. Bernstein.
Unfortunately, few doctors in general practic seem to be aware of this Diabetes-Tendon connection.
Even more unfortunately, improving blood sugars does not have an immediate effect on improving tendon problems. It may even be possible, though I have not seen this written up, that tendon problems, like other diabetic complications, may worsen at first when blood sugars are brought back to normal levels. That has been my own experience with these painful complications.
If you are diagnosed with a tendon problem and visit an orthopedic surgeon, he will usually suggest a cortisone shot. Though this may have a short term impact on your pain, the evidence shows it does not speed healing. In fact one study found,
At 6 weeks the analysis favoured the prednisolone group for most outcomes but none of the differences was significant. At 12 weeks, the analysis tended to favour the placebo group.
Since cortisone greatly worsens blood sugar control, and since some people with diabetes report that after cortisone treatment their blood sugar control worsened and did not return to its pre-treatment levels, cortisone poses dangers to people with diabetes that make it a poor choice for treatment, particularly since this study suggests you will heal better, long term, without it. Short course prednisolone for adhesive capsulitis (frozen shoulder or stiff painful shoulder): a randomised, double blind, placebo controlled trial
R Buchbinder et al. Annals of the Rheumatic Diseases
Sadly, orthopedic surgeons are not aware of this permanent worsening effect of cortisone on blood sugars and may brush off your stated concerns.
Alternative treatment for conditions involving painful tendons is the use of over the counter pain killers and patience. Physical therapy is often suggested for frozen shoulder. This therapy is very painful. It is hard to find high quality studies investigating the effectiveness of this therapy. But the one controlled trial that has been published in an obscure journal concluded:
At 3 weeks, 21 (35.0%) of 60 patients in the study group were considered to have had successful treatment compared with 11 (18.6%) of 59 in the control group (difference between groups 16.4%, 95% CI: 4.0-31.3, p=0.044). There was no significant difference in the success rate between the two groups at the 12th week follow-upEffectiveness of physical therapy for patients with adhesive capsulitis: a randomized controlled trial.
Pajareya K,J Med Assoc Thai
. 2004 May;87(5):473-80.