Not to mention the black market which existed with coaches and athletes adding to the state doping regimen. Usually the top coaches and athletes had the best back channel pharma hook up.
On top of this athletes in the GDR were notorious for their partying and alcohol abuse was rampant along with the doping. Poor diets, high doses of unknown drugs, you do the math.
Also, if they were to compare the health problems with Eastern Bloc countries which they were part of, the discrepencies amongst a lot of the rates are much less.