Glycemic Control Maintained over Time and Joint Stiffness in Young Type 1 Patients: What Is the Mathematical Relationship?

BACKGROUND

It is widely known that diabetes can induce stiffness and adversely affect joint mobility even in young patients with type 1 diabetes mellitus (T1D). The aim of this study was to identify a mathematical model of diabetes mellitus long-term effects on young T1D patients.

METHODS

Ankle joint mobility (AJM) was evaluated using an inclinometer in 48 patients and 146 healthy, sex- BMI-, and age-matched controls. Assuming time invariance and linear superposition of the effects of hyperglycemia, the influence of T1D on AJM was formalized as an impulse response putting into relationship past supernormal HbA1c concentrations with the ankle total range of motion. The proposed model was identified by means of a nonlinear evolutionary optimization algorithm.

RESULTS

AJM was significantly reduced in young T1D patients ( < .001). AJM in both plantar and dorsiflexion was significantly lower in subjects with diabetes than in controls ( < .001). The identified impulse response indicates that impaired metabolic control requires 3 months to bring out its maximum effect on the reduction of AJM, while the following long-lasting decay phase with the expected AJM recovery times, normally depends on the slow turnover of collagen. HbA1c concentration levels above 7.2% are sufficient to produce a reduction of ankle ROM.

CONCLUSIONS

In young patients with T1D the lack of glycemic control over time affects AJM. HbA1c levels can serve as a relevant prognostic factor for assessing the progression of LJM in subjects with diabetes.