**Background:** Over 500 million people live with diabetes worldwide. In Switzerland, diabetes prevalence is relatively low (6.3% in Lausanne, 2003–6), yet the country has the highest diabetes-related health expenditure globally (~US$13,000 per adult with diabetes). Good glycemic, blood pressure, and lipid control reduce complications and mortality, but no prior study had reported simultaneous control of these risk factors in a Swiss diabetes population. The study aimed to assess 15-year trends in glycemic, blood pressure, and cholesterol control in adults with diabetes from the CoLaus|PsyCoLaus cohort in Lausanne.
**Methods:** CoLaus|PsyCoLaus is a prospective population-based cohort of 6,733 adults aged 35–75 years at baseline (2003–6) in Lausanne, Switzerland. Participants were randomly selected from the city register (35% of eligible population invited). Three follow-ups occurred: 2009–12 (median 5.4 years), 2014–17 (median 10.7 years), and 2018–21 (median 14.5 years). Diabetes was defined as fasting plasma glucose ≥7 mmol/L and/or current glucose-lowering medication. Glycemic control was defined as FPG <7 mmol/L (and HbA1c <7% when available from 2014 onward). Blood pressure control was <140/90 mm Hg (stricter <130/80 mm Hg also assessed). Lipid control was non-HDL cholesterol <3.4 mmol/L (LDL <2.6 mmol/L also assessed). Simultaneous control required all three targets. Multivariate linear mixed-effects models identified factors associated with control, adjusting for sex, age, race, BMI, smoking, education, employment, marital status, and medication use.
**Key Results:** The number of adults with diabetes was 436 at baseline (6.5% prevalence), 539 at first follow-up (10.7%), 498 at second follow-up (10.9%), and 383 at third follow-up (11.4%). Diabetes awareness increased from 65.6% to 79.5% (second follow-up) then 73.7% (third follow-up). Median BMI remained stable (~29.2–29.7 kg/m²). Glycemic control (FPG <7 mmol/L) improved from 23.2% (95% CI 19.5–27.3) in 2003–6 to 32.8% (95% CI 28.1–37.8) in 2018–21, though it dipped to 19.2% in 2009–12. HbA1c <7% was achieved by 65.4% (2014–17) and 68.6% (2018–21). Blood pressure control (<140/90 mm Hg) rose from 51.5% (95% CI 46.8–56.2) at baseline to 63.3% (95% CI 58.2–68.1) at the third follow-up, plateauing after 2009–12. Stricter control (<130/80 mm Hg) improved from 24.6% to 31.7%. Lipid control (non-HDL <3.4 mmol/L) showed the largest improvement: 29.1% (95% CI 25.1–33.6) at baseline to 56.3% (95% CI 51.1–61.4) at the third follow-up. LDL <2.6 mmol/L increased from 31.3% to 54.4%. Simultaneous control of all three (FPG, BP, non-HDL) more than tripled from 5.5% (95% CI 3.7–8.1) at baseline to 17.2% (95% CI 13.7–21.5) at the third follow-up. When using HbA1c <7% instead of FPG, simultaneous control was 23.8% (2014–17) and 26.6% (2018–21). Medication use increased: glucose-lowering agents from 63.1% to 77.3%, blood pressure-lowering medication from 56.9% to 70.8%, and statins from 32.6% to 42.0%. Multivariate analysis showed men were less likely to achieve BP control (OR 0.91, 95% CI 0.86–0.97, p=0.005) but more likely to achieve non-HDL control (OR 1.08, 95% CI 1.02–1.15, p=0.007). Caucasians were less likely to achieve simultaneous control (OR 0.91, 95% CI 0.85–0.97, p=0.003). Treatment with glucose-lowering medication (OR 1.15, 95% CI 1.11–1.20, p<0.001) and statins (OR 1.08, 95% CI 1.05–1.12, p<0.001) were associated with better simultaneous control.
**Clinical Implications:** Cardiovascular risk factor control in adults with diabetes in Switzerland has improved substantially over 15 years, with simultaneous control more than tripling. However, only the SSED HbA1c target (≥40% achieving <7%) was met (68.6% in 2018–21). Blood pressure control (63.3%) fell short of the ≥65% target, and LDL cholesterol control (54.4%) missed the ≥63% target. Glycemic and blood pressure control plateaued or declined after 2014–17, possibly due to less aggressive treatment targets from clinical trials or COVID-19-related healthcare disruption. The study highlights persistent sex and racial disparities, with men less likely to control blood pressure and Caucasians less likely to achieve simultaneous control than non-Caucasians—a pattern opposite to that in the US. These findings underscore the need for continued efforts to improve diabetes care, particularly for blood pressure and lipid management, to meet national guidelines.