OBJECTIVES: The growing prevalence of diabetes leads to increased pressure on national healthcare budgets. Despite the high prevalence the long-term healthcare costs of diabetes patients are not widely studied in a clinical practice setting. The study objective was to quantify and describe healthcare resource utilization following newly-diagnosed type-2 diabetes mellitus (T2DM) patients over time.  METHODS: Newly diagnosed T2DM patients were identified from 84 primary care centers in Sweden between 1999 and 2009, and followed for a maximum of 9 years. Resource use data were extracted from electronic patient records (primary care contacts and laboratory tests) and a national patient register (hospitalizations). Data were linked using unique social security numbers. Resource use patterns are reported for the full study period and by partitioned time periods to investigate trends in resource use over time.  The relationship between weight and resource use was also investigated. RESULTS: The study included 38,956 T2DM patients (women, 45%; mean age, 64 years; HbA1c, 5.7%; mean BMI, 29.8) with a total number of 183,614 observation years. Over a mean follow-up of 4.7 years there were 2,134,870 (per patient mean 55) primary care contacts; 1,200,142 (31) laboratory tests and 24,656 (0.63) hospitalizations. Mean annual resource use almost doubled the first year after diagnosis and remained on a higher level than before diagnosis throughout the study period. This pattern was seen in primary care as well as for hospitalizations. Furthermore, obesity at baseline appeared to be correlated with a higher level of resource use. The relationship between resource use, baseline weight and weight changes appears complex. CONCLUSIONS: Data from 183,614 patient years of follow-up show that T2DM diagnosis is associated with increased long-term resource use. Quantifying resource utilization using data from clinical practice setting may provide an important input to diabetes cost-effectiveness modeling and resource allocation decisions.