According to Gram Research analysis, blood sugar control measured by hemoglobin A1c does not predict bone healing problems after foot and ankle surgery in diabetic patients. A 2026 retrospective study of 106 diabetic surgical patients found that A1c levels were not associated with healing failure, while higher body weight, elevated BMI, and lower vitamin D levels were significantly linked to poor bone healing outcomes.
A new study challenges what doctors thought they knew about diabetes and bone healing after foot and ankle surgery. Researchers looked at 106 diabetic patients who had foot or ankle operations and tracked how well their bones healed. Surprisingly, blood sugar control (measured by a test called hemoglobin A1c) didn’t predict whether bones would heal properly or fail to heal. Instead, the study found that body weight and vitamin D levels were much better predictors of healing problems. This finding could help doctors focus on the right things when preparing diabetic patients for foot surgery.
Key Statistics
A 2026 retrospective study of 106 diabetic patients undergoing foot and ankle surgery found that hemoglobin A1c levels were not associated with bone healing failure, contrary to common surgical assumptions.
In a study of 106 diabetic foot and ankle surgery patients, those who experienced nonunion had significantly higher body mass index (p=0.020) and lower vitamin D levels (p=0.014) compared to those with successful healing.
Among 106 diabetic patients reviewed in a 2026 study, 87 achieved successful bone union while 19 experienced nonunion, with body weight and vitamin D emerging as stronger predictors of healing outcomes than blood sugar control.
The Quick Take
- What they studied: Whether blood sugar control before foot and ankle surgery affects how well bones heal afterward in diabetic patients
- Who participated: 106 diabetic patients who had foot or ankle surgery between 2015 and 2020. Of these, 87 had successful bone healing and 19 experienced healing problems (nonunion)
- Key finding: Blood sugar control levels before surgery did not predict whether bones would heal properly. Instead, higher body weight, higher BMI, and lower vitamin D levels were strongly linked to healing problems
- What it means for you: If you have diabetes and need foot or ankle surgery, your doctor may focus more on your weight and vitamin D levels than on your recent blood sugar numbers when predicting healing success. This is preliminary research, so discuss your individual risk factors with your surgeon
The Research Details
Researchers reviewed medical records of 106 diabetic patients who had foot or ankle surgery over a five-year period (2015-2020). They collected information about each patient’s blood sugar control, body weight, smoking habits, vitamin D levels, and other health conditions. They then compared patients whose bones healed successfully with those who experienced healing problems (called nonunion, where bones don’t fuse together properly).
The study looked at hemoglobin A1c levels, which is a blood test that shows average blood sugar control over the previous three months. Doctors commonly use this test to assess surgical risk in diabetic patients. The researchers wanted to see if A1c levels could predict which patients would have healing problems after surgery.
This type of study is called a retrospective review, meaning researchers looked backward at existing medical records rather than following patients forward in time. While this approach is faster and less expensive than other study types, it can’t prove cause-and-effect relationships as strongly as some other research methods.
Understanding what actually predicts bone healing problems in diabetic patients is important because it helps surgeons better prepare patients and set realistic expectations. If blood sugar control isn’t the main factor, doctors can focus their efforts on the factors that actually matter, like helping patients reach healthier weights and ensuring adequate vitamin D levels before surgery
This study has moderate reliability. The sample size of 106 patients is reasonable for this type of research. However, because it’s a retrospective study looking at past records, it can’t prove that weight and vitamin D directly cause healing problems—only that they’re associated with them. The study was conducted at a single location, so results might differ in other populations. The findings are interesting but should be confirmed by larger, prospective studies before changing standard surgical practices
What the Results Show
The most surprising finding was that hemoglobin A1c levels—the standard blood sugar control measure—were not associated with bone healing problems. This held true whether researchers looked at blood sugar levels before surgery, the most recent blood sugar level, or changes in blood sugar over time. Even when researchers divided patients into categories based on clinically important A1c thresholds (like the commonly used 8% cutoff), there was still no connection to healing problems.
Instead, three factors showed strong associations with healing problems: body weight, body mass index (BMI), and vitamin D levels. Patients who experienced nonunion (failure of bones to heal) had significantly higher body weight and BMI compared to those whose bones healed successfully. They also had lower vitamin D levels. These three factors stood out as the most relevant predictors of healing complications.
Other factors that doctors might expect to affect healing—like age, sex, smoking status, peripheral neuropathy (nerve damage from diabetes), peripheral vascular disease (poor circulation), and chronic kidney disease—were not associated with healing problems in this study.
The study found that surgical location (which bone was operated on) did not significantly affect healing outcomes. Smoking status, which is often considered a risk factor for poor healing, was not associated with nonunion in this diabetic population. Peripheral neuropathy and peripheral vascular disease, both common complications of diabetes, also did not predict healing problems in this group
Previous research has suggested that poor blood sugar control impairs bone healing in diabetic patients. This study challenges that assumption by showing that A1c levels don’t predict healing outcomes in foot and ankle surgery specifically. The finding that body weight and vitamin D are more important aligns with other research showing these factors influence bone health and healing. However, this is one of the first studies to directly compare A1c’s predictive value against other factors in this specific surgical population
This study has several important limitations. First, it only included 106 patients from one location, so results might not apply to all diabetic patients or all surgical centers. Second, because it looked backward at medical records, researchers couldn’t control for all possible factors that might affect healing. Third, the study couldn’t prove that weight and vitamin D directly cause healing problems—only that they’re associated with them. Fourth, 19 patients experienced nonunion, which is a relatively small number for statistical analysis. Finally, the study didn’t measure how strictly patients followed post-surgery instructions, which could affect healing
The Bottom Line
If you have diabetes and need foot or ankle surgery: (1) Discuss your vitamin D levels with your doctor and consider supplementation if levels are low (moderate confidence); (2) Work toward a healthier body weight before surgery if possible (moderate confidence); (3) Don’t assume that perfect blood sugar control is the most critical factor for healing, though maintaining good diabetes management remains important for overall health (low-to-moderate confidence for this specific outcome). These recommendations are based on one study and should be discussed with your surgical team
This research is most relevant for diabetic patients planning foot or ankle surgery, their surgeons, and endocrinologists managing diabetes. It’s particularly important for patients whose doctors have emphasized blood sugar control as the main predictor of surgical success. However, this study shouldn’t replace personalized medical advice from your healthcare team
Bone healing after foot and ankle surgery typically takes 6-12 weeks for initial union, with complete healing taking several months. If healing problems develop, they usually become apparent within the first 3-6 months after surgery
Frequently Asked Questions
Does blood sugar control affect bone healing after foot surgery?
A 2026 study of 106 diabetic surgical patients found that hemoglobin A1c levels did not predict bone healing outcomes. Instead, body weight and vitamin D levels were stronger predictors of healing success or failure.
What factors actually predict poor bone healing in diabetic foot surgery?
Research shows higher body mass index and lower vitamin D levels are significantly associated with bone healing problems. These factors appear more relevant than blood sugar control for predicting surgical outcomes in diabetic patients.
Should I focus on blood sugar control before foot and ankle surgery?
While maintaining good diabetes management is important for overall health, this study suggests surgeons should also focus on vitamin D levels and body weight as predictors of healing. Discuss all three factors with your surgical team before scheduling.
What vitamin D level do I need for good bone healing after surgery?
The study found that lower vitamin D levels were associated with healing problems, though it didn’t specify an exact threshold. Most experts recommend maintaining vitamin D levels above 30 ng/mL. Ask your doctor about testing and supplementation before surgery.
Want to Apply This Research?
- Track vitamin D levels quarterly and body weight weekly. Set a goal to maintain vitamin D levels above 30 ng/mL (based on this study’s findings) and monitor BMI trends. If planning surgery, establish baseline measurements 3 months before the procedure
- Use the app to set reminders for vitamin D supplementation if levels are low, log weekly weight measurements, and create a pre-surgery preparation plan focusing on weight management and vitamin D optimization rather than obsessing over daily blood sugar numbers
- For patients planning foot/ankle surgery: establish a 12-week pre-surgery tracking period monitoring vitamin D levels, body weight, and BMI. Post-surgery, track healing progress through photos and symptom logs. Continue monitoring these factors for 6-12 months during the healing period
This research summary is for educational purposes only and should not replace professional medical advice. The findings are from a single retrospective study and should be confirmed by larger research before changing clinical practice. If you have diabetes and are considering foot or ankle surgery, discuss these findings with your surgeon and endocrinologist to develop a personalized treatment plan. Do not make changes to your diabetes management or surgical preparation based solely on this article without consulting your healthcare provider.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.