Background Diabetes mellitus is prevalent in Saudi Arabia. Our study aims to estimate the rate and time of developing macrovascular and microvascular complications in diabetic patients in a primary care setting. Methodology This is a retrospective cohort study. All collected data were retrieved using medical files and the electronic patient records of all diabetics having regular follow-ups in Family Medicine clinics, King Faisal Specialist Hospital & Research Centre in Riyadh, Saudi Arabia, from the beginning of January 2002 to the end of December 2018. The data included the demographics of patients diagnosed with diabetes mellitus, their HbA1c, and the follow-up duration of the development of complications, which included cardiovascular complications and diabetic nephropathy. Results We included 365 patients, of whom 47.1% males and 52.9% were females. The mean age of diabetes mellitus diagnosis in our population was 50 years (SD±11.3). The mean duration of follow-up was 7.14 years (SD±3.9). The rate of developing cardiovascular complications and diabetic nephropathy was 11.2% and 10.4%, respectively. The mean time to develop cardiovascular complications and diabetic nephropathy was 6 (SD±3.9) and 5.24 (SD±3.2) years, respectively. The mean time to develop the first diabetes complication was 5.5 years (SD±3.6). There was no statistical significance in the mean of HbA1c between patients who developed diabetic complications and those who did not. Conclusion Diabetes complications are common in the Saudi community. The duration of the development of cardiovascular complications and diabetic nephropathy was shorter than that indicated in international and national reports. Robust screening programs to diagnose and improve the control of diabetes mellitus should be established in the Kingdom.