A method of lag compensation of glucose level measurements, comprising: a) receiving at least three uncompensated glucose measurements prior to lag compensation, wherein the at least three uncompensated glucose measurements comprises a first uncompensated glucose measurement at an initial reference time, a second uncompensated glucose measurement at a first prior reference time, and a third uncompensated glucose measurement at a second prior reference time that is different from the first reference time; b) receiving (305; 405) reference glucose measurements; c) calculating a glucose point estimate based on the sum of the first uncompensated glucose measurement and at least first and second rates-of-changes weighted by first and second parameters, comprising: determining the first rate-of-change from a change computed from the first uncompensated glucose measurement at the initial reference time relative to the second uncompensated glucose measurement at the first prior reference time; determining the second rate-of-change from a change computed from the first uncompensated glucose measurement at the initial reference time to the third uncompensated glucose measurement at the second prior reference time; and using (310, 315; 410, 415) an error metric calculation involving an optimization routine to determine the first and second parameters based on the reference glucose measurements; d) calculating (320; 420) first and second weighting coefficients (d; b) based on the parameters; and e) calculating lag (325; 425)-compensated glucose level measurements from the uncompensated glucose measurements by adding values, weighted by the calculated weighting coefficients, of the corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time and the second prior reference time. a) receiving at least three uncompensated glucose measurements prior to lag compensation, wherein the at least three uncompensated glucose measurements comprises a first uncompensated glucose measurement at an initial reference time, a second uncompensated glucose measurement at a first prior reference time, and a third uncompensated glucose measurement at a second prior reference time that is different from the first reference time; b) receiving (305; 405) reference glucose measurements; c) calculating a glucose point estimate based on the sum of the first uncompensated glucose measurement and at least first and second rates-of-changes weighted by first and second parameters, comprising: determining the first rate-of-change from a change computed from the first uncompensated glucose measurement at the initial reference time relative to the second uncompensated glucose measurement at the first prior reference time; determining the second rate-of-change from a change computed from the first uncompensated glucose measurement at the initial reference time to the third uncompensated glucose measurement at the second prior reference time; and using (310, 315; 410, 415) an error metric calculation involving an optimization routine to determine the first and second parameters based on the reference glucose measurements; determining the first rate-of-change from a change computed from the first uncompensated glucose measurement at the initial reference time relative to the second uncompensated glucose measurement at the first prior reference time; determining the second rate-of-change from a change computed from the first uncompensated glucose measurement at the initial reference time to the third uncompensated glucose measurement at the second prior reference time; and using (310, 315; 410, 415) an error metric calculation involving an optimization routine to determine the first and second parameters based on the reference glucose measurements; d) calculating (320; 420) first and second weighting coefficients (d; b) based on the parameters; and e) calculating lag (325; 425)-compensated glucose level measurements from the uncompensated glucose measurements by adding values, weighted by the calculated weighting coefficients, of the corresponding uncompensated glucose measurements received at the initial reference time, the first prior reference time and the second prior reference time.