A mathematical model of the effect of metabolic control on joint mobility in young type 1 diabetic subjects

Diabetes mellitus is a metabolic disorder representing one of the main problems for the global public health. The impairment of metabolic control can influence periarticular tissue and other major risk factors of limited joint mobility (LJM) also in young type 1 diabetic patients. LJM is a widespread phenomenon in diabetic patients and it is often characterized by ankle stiffness. In particular, a deficit of ankle joint mobility may occur with the onset of the disease; later, this deficit tends to deteriorate in presence of a poor glycemic control. We hypothesized a mathematical model of diabetes mellitus long-term effects, assuming that a reduced metabolic control affects joint mobility according with a Gaussian function: it requires some time for developing a reduction of joint mobility, that persists for a stable period, before fading out with time (in case metabolic control has been recovered). A non-linear optimization estimated the model parameters for obtaining the best fit over a set of patients. Results are in good accordance with empirical estimates: lack of control needs to persist for at least a few months before generating a sensible effect, that persists for up to one year.