Higher fasting blood sugar worsens knee symptoms in patients with knee osteoarthritis

The authors suggest healthcare providers pay attention to controlling blood sugar, specifically in patients with knee osteoarthritis and concurrent central sensitization to reduce their knee symptoms.

Cross-sectional and cohort data have suggested that higher serum blood glucose levels in patients with KOA are linked with more severe knee symptoms; more is needed about the longitudinal relationship between serum blood sugar and knee symptoms, especially considering CS comorbidity, which also deteriorates knee symptoms.

Against the above background, Daisuke Chiba from Hirosaki University Graduate School of Medicine in Aomori, Japan, and colleagues aimed to assess the longitudinal relationship between fasting blood sugar (FBG) at baseline and change in knee symptoms based on central sensitization comorbidity. They hypothesized that a higher FBG level is more likely to cause a decline in knee symptoms in patients with knee osteoarthritis and comorbid CS.

The authors enrolled 297 participants (mean age: 59.6 years) in the study. At baseline, the evaluation of plain radiographs of the bilateral knee joints was done according to the Kellgren–Lawrence grade (KLG). All patients showed at least a KLG ≥ 2 in each knee. Fasting blood sugar and Central Sensitization Inventory-9 (CSI-9) were assessed at baseline; more than 10 points on the CSI-9 were defined as CS+. KOOS (Knee injury and Osteoarthritis Outcome Score) was investigated at baseline and a follow-up of 1 year; ΔKOOS (change in KOOS) was calculated by subtracting the KOOS at baseline from KOOS at the follow-up of 1 year. ΔKOOS was taken as the dependent variable, and the independent variable was FBG after adjustments for sex, age, CSI-9, and BMI at baseline.

The key findings of the study were:

· Of the 297 subjects, 16.2 % were defined as CS+. In the CS − group, no association was found between FBG levels at baseline and ΔKOOS.

· FBG at baseline was negatively linked with ΔKOOS pain (B = − 0.448), ADL (B = − 0.438), and sports (B = − 0.706).

To sum up, higher FBG levels at the baseline deteriorated knee symptoms in radiographic knee osteoarthritis and comorbid CS patients during a follow-up of 1 year. On the other hand, fasting blood sugar was not longitudinally associated with knee symptoms.

"There was a negative association between CS comorbidity and KOOS scores at baseline for patients with radiographic KOA. However, CS itself did not impact longitudinal changes in KOOS," the authors wrote. "Therefore, comorbid CS deteriorated knee symptoms in radiographic KOA patients only when their fasting blood sugar was increased."

Reference:

Chiba, D., Ohyama, T., Sasaki, E. et al. Higher fasting blood glucose worsens knee symptoms in patients with radiographic knee osteoarthritis and comorbid central sensitization: an Iwaki cohort study. Arthritis Res Ther 24, 269 (2022).

https://doi.org/10.1186/s13075-022-02951-2