As everyone knows, diabetics commonly experience hypoglycemia (low blood sugar levels). And what are the symptoms? Slow and slurred speech, poor balance, impaired motor control, staggering, drowsiness, flushed face, disorientation - in other words, the classic symptoms of alcohol intoxication. This individual will look and act like a drunk driver to the officer, and will certainly fail any DUI "field sobriety tests". As one expert has observed, "Hypoglycemia (abnormally low levels of blood glucose) is frequently seen in connection with driving error on this nation's roads and highways...Even more frequent are unjustified DUIs or DWIs, stemming from hypoglycemic symptoms that can closely mimic those of a drunk driver." From "Hypoglycemia: Driving Under the Influence" in 8(1) Medical and Toxicological Information Review Sept. 2003.
What the Breathalyzer Measures
Ignoring for the moment the inherent inaccuracy and unreliability of these machines, most suffer from a little-known design defect: they do not actually measure alcohol! Rather, they use infrared beams of light which are absorbed by any chemical compound (including ethyl alcohol) in the breath which contains the "methyl group" in its molecular structure; the more absorption, the higher the blood-alcohol reading. The machine is programmed to assume that the compound is "probably" alcohol.
Diabetes and the Breathalyzer
Unfortunately, thousands of compounds containing the methyl group can register as alcohol. One of these is "acetone". And a well-documented by-product of hyperglycemia is a state of DKA or "Diabetic Ketoacidosis", which causes the production of acetones in the breath. In other words, the Breathalyzer will read significant blood alcohol levels on the breath where there may be little or none. See, for example, Brick, "Diabetes, Breath Acetone and Breathalyzer Accuracy: A Case Study", 9(1) Alcohol, Drugs and Driving (1993).
But this rarely happens, right? Fact: roughly one in seven sober drivers on the road suffers from diabetes.