Does serum cystatin C level reflect insulin resistance in patients with type 1 diabetes?

The aim of study was to evaluate the relationship between serum cystatin C and insulin resistance (IR) in type 1 diabetic patients being the participants of Poznan Prospective Study.

The study was performed on 71 Caucasian patients (46 men); with type 1 diabetes, who were recruited into the Poznan Prospective Study, at the age of 39±6.1 meanly, and treated with intensive insulin therapy since the onset of the disease. The follow-up period and diabetes duration were 15±1.6 years. Insulin resistance (IR) was assessed by estimated glucose disposal rate (eGDR) calculation with cut-off point 7.5 mg/kg/min. Patients were divided into two groups, according to the presence or absence of IR.

From among 71 patients, 31 patients (43.7%) presented decreased sensitive to insulin with eGDR below 7.5 mg/kg/min. Patients who had eGDR <7.5 mg/kg/min (insulin resistant), compared with subjects with eGDR >7.5 mg/kg/min (insulin sensitive), had higher level of serum cystatin C [0.59 (IQR:0.44-0.84) vs 0.46 (IQR:0.37-0.55) mg/L, p=0.009]. A significant negative correlation between cystatin C and eGDR was revealed (Rs=-0.39, p=0.001). In regression model cystatin C was related to insulin resistance, adjusted for sex, BMI, eGFR and duration of diabetes [OR 0.03 (0.001-0.56), p=0.01].

Higher level of serum cystatin C is related to decreased insulin sensitivity in patients with type 1 diabetes. This relationship seems to have an important clinical implication.