Here is part of the abstract of a new NBER paper from Gisela Hostenkamp and Frank R. Lichtenberg:
We use Danish diabetes registry and health insurance data to analyze the extent, consequences, and determinants of under-use and overuse of oral anti-diabetic drugs.
Less than half of patients consume the appropriate amount of medication–between 90% and 110% of the amount prescribed by their doctors.
The life expectancy of patients consuming the appropriate amount is 2.5 years greater than that of patients consuming less than 70% of the prescribed amount, and 3.2 years greater than that of patients consuming more than 130% of the prescribed amount, controlling for time since diagnosis, insulin dependence, comorbidities, age, gender and education. Patients consuming the appropriate amount are also less likely to be hospitalized than under- or over-users.
And of course that is from Denmark, which is supposed to be a culture with relatively strong norms of conscientiousness.