Insulin-like growth factor-1 status is associated with insulin resistance in young patients with spinal muscular atrophy

Insulin-like growth factor-1 (IGF-1) is an anabolic hormone with myotrophic effects on muscle tissue. Patients with spinal muscular atrophy (SMA) sustain early-onset sarcopenia, which contributes to an increased prevalence of insulin resistance. Our aim was to determine the IGF-1 status in 5q-SMA patients and its association with insulin resistance. Real-life clinical and laboratory data of 34 patients (15 males; age 3 months-24 years) included: anthropometric measurements [weight, height/length, body mass index or weight-to-length ratio, delta-height standard deviation score (∆Ht SDS) as the difference between height/length SDS and mid-parental height (MPHt) SDS] and laboratory measurements [Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and IGF-1]. HOMA-IR levels categorized patients as insulin-resistant [HOMA-IR ≥1.9 (n = 20)] or insulin-sensitive [HOMA-IR <1.9 (n = 14)]. The collective height/length SDS was −0.29±1.34 and ∆Ht SDS was −0.11±1.47. IGF-1 levels were within the normal population range for all patients. Insulin-resistant patients had higher IGF-1 SDS levels compared to insulin-sensitive patients (0.87±0.78 vs. −0.67±0.96, respectively, P<0.001). The IGF-1 SDS was significantly associated with HOMA-IR for all subjects (r = 0.547, P = 0.001), and linear growth parameters (height/length SDS, ∆Ht SDS) were significantly associated with IGF-1 SDS in the insulin-resistant subgroup (r = 0.649, P = 0.002 and r = 0.605, P = 0.005, respectively). Our findings suggest that IGF-1 status is associated with insulin resistance in patients with early-onset sarcopenia.