Changes in HbA1c levels and body mass index after successful decompression surgery in patients with type 2 diabetes mellitus and lumbar spinal stenosis: results of a 2-year follow-up study

Abstract

Background context: Lumbar spinal stenosis (LSS) can hinder a patient's physical activity, which in turn can impair glucose tolerance and body weight regulation in patients with type 2 diabetes mellitus (DM-2). Therefore, successful lumbar surgery could facilitate glycemic control and body weight regulation.

Purpose: This study aimed to evaluate the effects of postoperative improvement in physical activity on body mass index (BMI) and hemoglobin A_1c (HbA_1c) level in patients with LSS and DM-2 over a 2-year follow-up period.

Study design: Prospective longitudinal observational study.

Patient sample: Patients with LSS and DM-2.

Outcome measures: Visual analogue scale (VAS) scores for back pain and leg pain, Oswestry Disability Index (ODI) scores, Japanese Orthopaedic Association (JOA) scores, JOA Back Pain Evaluation Questionnaire (JOABPEQ) sections, BMI, and blood analysis for HbA_1c were carried out.

Methods: A total of 119 patients were enrolled for analysis of the effect of successful decompression surgery on changes in HbA_1c levels and BMI. The VAS score, ODI score, JOA score, JOABPEQ, BMI, HbA_1c were reassessed at 6 months, 1 year, and 2 years after surgery. Additionally, correlations between changes in HbA_1c and changes in the ODI, JOA, JOABPEQs, and BMI were analyzed.

Results: The overall values of HbA1c before and at 6 months, 1 year, and 2 years after the surgery were 7.08±0.94%, 6.58±0.87%, 6.59±0.79%, and 6.59±0.79%, respectively (p-values; 6 months: .024; 1 year: .021; 2 years: .038). In the not well-controlled sugar (non-WCS) group (preoperative HbA_1c>6.5%), the difference between pre- and postoperative HbA_1c was highly statistically significant (p<.01). The overweight group (preoperative BMI≥25) showed statistically significant BMI reduction in the second year after surgery (p=.034). The postoperative HbA_1c changes are strongly correlated with the improvements of ODI, JOA, and JOABPEQ after surgery.

Conclusions: The present study demonstrates that in patients with DM-2 and LSS, successful lumbar surgery may facilitate glycemic control by enabling an increase in the patient's level of physical activity. Additionally, it could help reduce body weight in overweight (BMI>25) patients with DM-2 and LSS.

Keywords: Body mass index; Hemoglobin A(1c); Lumbar spinal stenosis; Lumbar surgery; Physical activity; Type 2 diabetes mellitus.