It is often said that the introduction of
insulin into clinical medicine made a 'dramatic' difference to the mortality resulting from
diabetic coma. This is true in the sense that before 1922 it was almost uniformly fatal, but until the 1950s the mortality in many large hospitals was as high as 30-50%. Often autopsy did not establish a cause of death. Many may have been a result of hypokalaemia, a complication which was not recognized until 1946; in that year in the Journal of the American Medical Association, Jacob Holler described a patient who developed
respiratory paralysis 12h into treatment that, after several hours in an
iron lung, was cured by
potassium infusion. In the 5 years after Holler's paper there were many reports of deaths resulting from hypokalaemia, as well as several 'near misses', but clinicians were extremely cautious about early replacement probably, as an editorialist in The Lancet suggested, because 'the frightening effects of
intravenous injections of
potassium made clinicians reluctant to believe in a lack of
potassium as a cause of trouble, except in very rare conditions such as
familial periodic paralysis'. It had been known since 1923 that
insulin lowered serum
potassium, but this was not of great interest because the symptoms of hypokalaemia were not known. Also,
potassium was not an
electrolyte with which clinicians were familiar. Until the introduction of flame photometry in 1950, it was only measured in research studies as chemical methods took several hours to complete.