Spanish Study Links Chronic Back Pain, Diet Quality, and Blood Sugar Control

A study from Spain has uncovered a compelling connection between chronic low back pain (CLBP), lifestyle habits, and impaired blood sugar regulation — findings that could reshape how American patients and their doctors think about managing both pain and metabolic health simultaneously.

Conducted by researchers at Rey Juan Carlos University in Madrid and published in Pain Physician (2025), this secondary analysis examined what lifestyle factors best predicted poor blood sugar responses after consuming a high-glycemic index sugary drink. The results point to a cluster of modifiable risk factors that go well beyond diet alone.

What the Researchers Did

Participants with chronic low back pain consumed either a sucrose beverage (high glycemic index) or isomaltulose (lower glycemic index) in a randomized crossover design. Researchers then measured postprandial (after-meal) blood glucose responses using finger-prick monitoring and analyzed which baseline factors predicted the worst glycemic spikes. Body composition, dietary quality, physical activity, psychological health, and dietary inflammation scores were all assessed.

Key Findings

Five factors emerged as significant predictors of a worse blood sugar response after the sugary drink:

• Higher body weight — more weight corresponded to a larger blood sugar spike
• Older age — older participants showed greater postprandial glucose elevations
• More pro-inflammatory diet — diets higher in inflammatory foods worsened glycemic response
• Poorer mental health — worse psychological wellbeing predicted higher blood sugar spikes
• Lower overall diet quality — participants eating lower-quality diets had significantly impaired responses

In US units, a meaningful postprandial blood sugar spike is generally defined as a reading above 140 mg/dL (7.8 mmol/L) at two hours after eating — a threshold the American Diabetes Association uses to identify impaired glucose tolerance. Repeated spikes above this level are associated with progression toward type 2 diabetes.

Why This Matters for US Patients

Chronic low back pain affects roughly 65 million Americans, making it one of the most common conditions seen in primary care. What makes this Spanish research particularly valuable for US patients is its focus on the overlap between pain conditions and metabolic health — an intersection often overlooked in American clinical practice, where pain management and diabetes care are typically handled in separate silos.

Current US guidelines from the American Diabetes Association emphasize diet quality, weight management, and mental health as pillars of diabetes prevention — all factors this Spanish study independently confirmed as predictors of poor glycemic control. What's new here is the specific link to chronic pain patients, who may face unique barriers to healthy eating and physical activity.

The mental health finding is especially relevant: depression and anxiety are both more common among chronic pain sufferers and among people with diabetes. This study suggests that addressing psychological wellbeing may directly support better blood sugar outcomes — not just quality of life.

Important caveats: this study was conducted exclusively in women, so findings may not apply to men. Blood sugar was measured with a basic finger-prick device rather than continuous monitoring, and causal conclusions cannot be drawn from this design.

The Bottom Line

If you have chronic low back pain and are concerned about your blood sugar, talk to your doctor about a comprehensive lifestyle review — including diet quality, anti-inflammatory eating patterns, and mental health support. This Spanish research reinforces that these factors are interconnected, not isolated.

Source: Gonzalez-Alvarez E, et al. "Lifestyle Habits as Potential Predictors of Impaired Blood Glucose Regulation in Patients with Chronic Low Back Pain vs. Healthy Controls." Pain Physician. 2025. PMID: 41337765.