He could have been diabetic three days before the diet started. Or three months.

Nobody on the "Low carb raises blood glucose" who wasn't diabetic prior to the diet is clearly diabetic now. Glucose intolerance, slight elevations in fasting blood glucose, is not diabetes. CoachJeff has even come to the point where it looks like his elevated blood glucose might have been caused by a vial of faulty blood glucose strips giving falsely high readings.




There's two separate issues here.



One; a healthy person with normal blood glucose on a higher carb diet is more likely to show glucose intolerance on a high fat, low-carb diet. This is normal, the body switches over to a high fat metabolism, it's poorly adapted to more than habitual intake of glucose. This is not diabetes or prediabetes.

Two; for some people, an extremely high carb, low fat diet like the Rice Diet does seem to reverse diabetes. In a glucocentric universe, this is called diabetes reversal vs. normal glucose achieved with a very low carbohydrate diet. But people on the Rice Diet are just as fat-intolerant as people on very low carb are glucose intolerant--go back to a high fat and high carb diet, from either direction, and diabetes will return.