In order to compare the prevalence of T2DM among patients with CTS with the general population, a control group was formed consisting of operatively treated herniated nucleus pulposus (HNP) patients. HNP patients were chosen assuming that HNP patients would be derived from about the same age category as the CTS group and because it is a frequently diagnosed disease which makes it possible to build a control group consisting of enough patients. Finally only operated patients were chosen because DM status and BMI data are known for the majority of operated patients in our hospital. Patients in the control group were treated in the same period as the CTS group.
They were excluded when they received an operation because of a relapse or had received the diagnosis CTS in the past.