Techniques are used for adaptation of drug-administration parameters that control insulin delivery in a blood glucose control system. One technique provides long-term adaptation of a nominal basal infusion rate, adapting to longer-term changes in a patient's needs due to growth, illness, hormonal fluctuations, physical activity, aging, etc. Another technique provides adaptation of priming dose size at mealtimes for overall better glycemic control and also adapting to longer-term changes in a patient's needs. Adaptation calculations use a receding-horizon window of recent values of the adapted parameter. Doses of a counter-regulatory agent (e.g., glucagon) may also be delivered in response to information about estimated accumulation of exogenously infused insulin (subcutaneously, intramuscularly, intraperitoneally, or intravenously) and/or the effect insulin might have on glucose levels (blood glucose concentration or interstitial fluid glucose concentration).