Abstract
During the course of a study on human subjects involving the effect of the breakfast meal on carbohydrate metabolism, 1 seasonal variation in fasting blood sugar levels was noted.
Work done in this laboratory over a 2 year period on 9 women gave a total of 170 fasting blood sugar determinations. When these values were averaged by months, the results shown in Fig. 1 were obtained. The fasting values during the 2 year period were within the range given by Peters and Van Slyke. 2 However, they showed marked seasonal differences. Blood sugar concentration rose progressively with the colder months of the year and were definitely higher in the winter than during the summer months.
The subjects used in this study were 9 women laboratory workers ranging in age from 28 to 48 years They were of average weight and height and moderately active. They were considered to be in good health although no physical or medical examinations were made.
Periodic blood counts and urine analyses were normal. At no time did any of the subjects participate in an experiment when suffering from a cold or similar indisposition. Neither were tests made during menstruation. By coincidence none of the subjects were smokers.
Samples of blood were taken after 15 hours' fasting and collected from a fingerprick into a paraffin well. Folin's micro method 3 was used for the glucose determinations, using 1.6% sodium carbonate in place of the sodium cyanide-sodium carbonate solution as recommended by Klendshoj and Hubbard. 4 Readings were made on a Beckman spectrophotometer at 5200 Å. All measurements and readings throughout the study were done by the same analyst. Periodic standard sugar curves were made to check the solutions and the instrument.
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