Potential of prevention strategies for the modifiable risk factor type 2 diabetes with relation to the future number of dementia patients in Germany– a multi-state projection through 2040

BACKGROUND: We assess the impact of prevention strategies regarding type 2 diabetes as a modifiable risk factor for dementia and its consequences for the future number of dementia patients in Germany. METHODS: We used a random sample of health claims data (N = 250,000) of insured persons aged 50+ drawn in 2014, and data on population size and death rates in 2015 from the Human Mortality Database. Using exponential hazard models, we calculated age- and sex-specific transition probabilities and death rates between the states (no diabetes/no dementia, diabetes/no dementia, no diabetes/dementia, diabetes/dementia). In multi-state projections, we estimated the future number of dementia cases aged 75+ through 2040 depending on the development of the incidence of diabetes among persons without diabetes and without dementia, and the dementia incidence among persons with and without diabetes. RESULTS: In 2015 there were 1.53 million people with dementia aged 75+ in Germany. A relative annual reduction in death rates of 2.5% and in dementia incidence in persons without diabetes of 1% will increase this number to 3.38 million by 2040. A relative reduction of diabetes incidence by 1% annually would decrease dementia cases by around 30,000, while a reduction of dementia incidence among people with diabetes by 1% would result in 220,000 fewer dementia cases. Both prevention strategies combined would prevent 240,000 dementia cases in 2040. CONCLUSIONS: The increase in life expectancy is decisive for the future number of people with dementia. Strategies of better diabetes treatment have the potential to lower the increase in the number of dementia patients in the coming decades. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12883-022-02682-6.