RT Journal A1 MARK MF T1 OPtimum time for administration of protamine zinc insulin JF Archives of Internal Medicine JO Archives of Internal Medicine YR 1939 FD November 1 VO 64 IS 5 SP 897 OP 906 DO 10.1001/archinte.1939.00190050003001 UL http://dx.doi.org/10.1001/archinte.1939.00190050003001 AB Hagedorn, Norman Jensen, Krarup and Wodstrup,1 who were the first to use protamine insulin, gave in most of their cases a dose of protamine insulin in the evening and one of regular insulin in the morning. The addition of zinc to protamine insulin by Scott and Fisher2 prolonged the action of the new preparation considerably, so that a single injection a day was sufficient to control the diabetes in a large percentage of cases.. Sprague and his associates3 adopted the procedure of giving the single dose of protamine zinc insulin early in the morning, and their method was soon followed by most investigators (Campbell and his associates,4 Joslin,5 Rabinowitch6 and others). In previous studies (Mosenthal7 and Mark, Sackey and Mosenthal8) in which a single dose of protamine zinc insulin was administered at 6 or 7 a. m., it was found that there was a rise of the level of sugar