Background Type 2 diabetes is one of today's major public health challenges. Registered Nurses within the primary health care sector possess the ability to support these patients towards a healthier life. Aim The aim of this study was to explore which factors correlate the most with HbA1c in patients with type 2 diabetes. Method A quantitative study of 1142 primary health care patients was conducted using data obtained from the Swedish National Diabetes Register from 2015. Multilinear regression was used to establish correlations between HbA1c and the factors Exercising, Body Mass Index (BMI), Smoking and Waist Circumference. The strength of correlations was tested using Pearson's correlation test. Descriptive statistics were used to further analyse the named factors. Results Exercising more than three times weekly was associated with a statistically significant decrease in HbA1c by 3,8 units. Smoking produced a 1,3 unit increase in HbA1c, a finding that was not proven statistically significant. High BMI and Waist Circumference was associated with increases in HbA1c by 0,36 and 0,15 units respectively with both findings proving statistically significant. Conclusion The Registered Nurse within primary health care should emphasise guiding patients to exercising and to quit smoking while also guiding (encouraging) them in other lifestyle changes