Prevalence and consequences of spinal pain among people with type 1 and type 2 diabetes mellitus in Denmark

Diabetes mellitus (DM) is a chronic disease characterised by high blood glucose levels, affecting one in 10 adults worldwide [1]. In Denmark, one in 20 adults suffered from DM in 2018, while the prevalence is expected to almost double by 2030 [2, 3]. The two main types of DM include the autoimmune type 1 with absolute insulin insufficiency and type 2 with insulin resistance [4]. Type 2 DM accounts for the majority of cases (85–95%) in high-income countries [1], and physical inactivity and obesity are among commonly known risk factors [5, 6].

DM is associated with comorbidities and medical complications that increase the risks of morbidity and mortality [7], which in turn negatively impact the individual’s quality of life [8]. Musculoskeletal (MSK) pain is more common in people with DM compared with the general population [9‐11]. DM is associated with a range of common MSK conditions such as osteoarthritis, fragility fractures, neuropathy, and rheumatoid arthritis [12‐15]. Even though there is an increased incidence of rare spine diseases such as epidural abscess and vertebral osteomyelitis in DM, more common disorders that cause chronic back pain such as lumbar disc degeneration, spinal stenosis and generally reduced joint mobility have also been linked to DM [16, 17]. Less known, however, is whether people with DM also suffer from more common non-specific spinal pain that are endemic in the general population [18].

In Denmark, more than half of the general population report MSK pain during the past 14 days, and cervical and lumbar pain contribute with the largest disease burden—e.g. being one of the main causes of long-term sick leave, early retirement as well as hospital admissions and visits to general practitioners [18, 19].

Previous studies indicate that people with DM report spinal pain more frequently than people without DM, but these studies do not consider DM types, or do not focus on specific pain sites [9, 12]. Physical activity and exercise is recommended for people with DM, but MSK pain is a known barrier to being physically active [20]. Furthermore, having chronic diseases and additional MSK pain can result in a higher healthcare load and treatment burden, but it is unknown [21].

The aim of the present study is to describe the prevalence and characteristics of pain in the spine (cervical, thoracic, lumbar) in people with type 1 and 2 DM from two large Danish secondary DM care centres. Secondly, to describe the consequences of this pain in relation to physical activity during leisure time and at work, and care-seeking behaviour. Finally, to compare the spinal pain prevalence and consequences to a population-based reference cohort from the Danish Twin Registry, because spinal pain is common in the general population [22, 23].

We distributed the questionnaire to 10,582 people with DM, and data from 3767 people were analysed (36.0% response rate) (Fig. 1). Men accounted for 59.8% of the sample, and most of the people were between 51 and 70 years (Table 1) [24]. Participants with type 1 DM accounted for 43.2% of the cohort, and participants with type 2 DM tended to have lower educational level and be less physically active than participants with type 1 DM.

In this questionnaire study covering 3767 people from two large secondary care centers in the Region of Southern Denmark, spinal pain was common in people with type 1 and 2 DM, with lumbar pain having the highest prevalence and more frequently reported in type 2 DM as compared to type 1 DM. Women had a higher pain prevalence for any spinal region for both DM types, while estimates were higher for cervical and thoracic pain for people < 60 years compared with ≥ 60 years. Spinal pain considerably impacted people´s leisure time, work life, and healthcare utilisation. A larger proportion of people with type 2 DM and spinal pain experienced pain-related consequences.

People with DM reported a significantly higher prevalence of spinal pain when compared to a Danish population-based cohort. In the Danish Twin registry study of 34,902 Danish adults aged 20–71 using the same questionnaire (i.e. Standardised Nordic Questionnaire [26]), the overall pain prevalence within the past year was most frequently reported for the lumbar spine (43%), which is similar to the 43.9% reported for the Dutch population [23, 30]. This is comparable to the prevalence of lumbar pain in people with type 1 DM (41.3%) in our study, but lower than what we saw in people with type 2 DM in our study (49.6%) [23]. Cervical pain was reported by 30% in Danish adults and 31.4% in Dutch adults, which were lower than what was reported in our study for people with type 1 and type 2 DM (35.1 and 34.9% respectfully) [23, 30]. Thoracic pain was reported by 13% in Danish adults and 18.8% in Dutch adults, which were lower than both DM types (18.5 and 20.5%). When comparing our data with population-based samples of Danish adults using different definitions and methodologies, the prevalence in people with DM is considerably higher [31].

In our recent study, MSK pain in the upper and lower extremities on the same diabetes cohort was presented [29]. The 1-week prevalence in type 1 DM was highest for the shoulder (30.8%) and hand (23.0%), which were higher than lumbar pain (24.6%) and cervical pain (21.2%). For type 2, the highest 1-week prevalence estimates were reported for the shoulder (30.5%), ankle (29.8%), and knee (28.2%), comparable with lumbar pain (32.4%), but lower for the cervical pain (21.6%). The 1-year prevalence in type 1 DM was highest for the shoulder (41.8%), followed by the lumbar spine (41.3%), cervical spine (35.1%), hand and knee (both 32.2%), and ankle (29.6%). For type 2 DM, the highest prevalence was reported for the lumbar spine (49.6%), followed by the shoulder (40.5%), knee (40.3%), ankle (38.1%), and cervical spine (34.9%). Similar to our findings, a higher proportion of women reported MSK pain compared with men in populations with DM [9, 29, 31]. The higher prevalence of pain in women compared with men is in line with results from other studies of the general populations [32, 33]. Our findings add to the growing evidence—with caveats related to variations in the estimates across gender and age groups—that MSK pain is very common in people with DM.

Besides looking at the prevalence of pain, it is also important to compare symptom duration and chronicity. In our data, a substantially higher proportion reported having had lumbar pain for more than 30 days during the past 12 months than in the general population (58.6 vs. 12%) [22, 23]. The same pattern was observed for both cervical and thoracic pain regions (cervical 57.2 vs. 10%, thoracic 56.9 vs. 4%) [22, 23]. These data indicate that people with DM and concomitant spinal pain have more persistent pain than in the general population.

A relatively high proportion of people in our study reported that spinal pain influenced their ability to be physically active during leisure time (ranging from 43.7 to 63.9% across body regions for the total group) and at work (20.7–33.3%), and many sought care (44.3–48.5%). The consequences of spinal pain in the general population in Denmark has been scrutinised, allowing us to make direct comparisons [22]. In the general population, reduced daily activities was reported by 4–17%, and 6–17% had sought care because of spinal pain, which are considerably lower estimates than in our cohort. Furthermore, 2–8% changed work or work duties in the general population compared with 16.0–31.3% in our study. Looking at people without DM with spinal pain [22], 38–40% reported care-seeking within the last 12 months, and the proportion was 42.2% in a large Dutch study, [30] compared with 44.3–48.5% in our study. However, 23% (any duration) [22] and 6.1% (duration > 4 weeks) [30] of the populations without DM with spinal pain reported sick leave during the last 12 months  because of lumbar pain compared with our findings, where 28.1% were prevented from working > 30 days during the last 12 months, again highlighting that although pain prevalence might be similar in (a) the general population, (b) people without DM with spinal pain, and (c) people with DM and spinal pain, the consequences have greater impact on the individual’s life and may last longer for the latter group. Besides being a potential obstacle to physical activity, MSK pain can negatively impact multiple aspects of patient health, including cognitive processes and brain function, mood/mental health, sleep, cardiovascular health, and quality of life [34]. An individual with both DM and MSK pain (i.e. multimorbidity) has a greater risk of poorer function, quality of life, increased healthcare utilisation, and premature death, and in people with back pain an increasing number of comorbidities is associated with poorer short-term and long-term pain and functional outcomes [21, 35].

Our data support that clinicians should focus on identifying MSK pain/limitations in people with DM, with particular focus on the different spine regions, DM types, gender, and age, due to the considerable prevalence and consequences for the individual. Person-centred care is recommended to manage multimorbidity, but there is still limited evidence to support any specific approach [21]. However, the complications may be reduced by identifying MSK problems early to promote physical activity—a cornerstone in the treatment of DM—[11, 12, 36, 37] and recent promising initiatives for the global treatment of multimorbidity have the potential to benefit people with DM and MSK pain in order to improve their self-care behaviors [21].

Spinal pain is common in people with type 1 and 2 DM from Denmark, leading to considerable consequences for leisure/work physical activity, sick-leave, and healthcare utilisation. A larger proportion of people with type 2 DM than type 1 DM is affected by the consequences of spinal pain. The prevalence of spinal pain in populations with DM is higher than in the general population, and people with both spinal pain and DM report more consequences of their pain, particularly in relation to work.