Association between low internal health locus of control, psychological distress and insulin resistance. An exploratory study

AIM: To assess the hypothesis that low internal health locus of control (IHLC) and psychological distress (PD) are associated with insulin resistance. MATERIALS AND METHODS: In 2002-2005, a random population sample of 2,816 men and women aged 30-74 years participated (76%) in two municipalities in southwestern Sweden. This study included 2,439 participants without previously known diabetes or cardiovascular disease. IHLC was measured by a global scale and PD was measured by the 12-item General Health Questionnaire. Insulin resistance was estimated using HOMA-ir. General linear models were used to estimate differences in HOMA-ir between groups with low IHLC, PD, and both low IHLC and PD, respectively. RESULTS: Five per cent (n = 138) had both PD and low IHLC, 62 per cent of participants (n = 1509) had neither low IHLC nor PD, 18 per cent (n = 432) had PD, and 15 per cent (n = 360) low IHLC. Participants with both low IHLC and PD had significantly higher HOMA-ir than participants with neither low IHLC nor PD (Δ = 24.8%, 95%CI: 12.0-38.9), also in the fully adjusted model (Δ = 11.8%, 95%CI: 1.5-23.0). Participants with PD had significantly higher HOMA-ir (Δ = 12%, 95%CI: 5.7-18.7), but the significance was lost when BMI was included in the model (Δ = 5.3%, 95%CI:0.0-10.8). Similarly, participants with low IHLC had significantly higher HOMA-ir (Δ = 10.1%, 95%CI: 3.5-17.0) but the significance was lost in the fully adjusted model (Δ = 3.5%, 95%CI: -1.9-9.3). CONCLUSIONS: Internal health locus of control (IHLC) and psychological distress (PD) were associated with insulin resistance. Especially individuals with both PD and low IHLC may need special attention.