If he's only recently started testing his blood glucose, when already low carb--you don't have a baseline. You could have him test his blood glucose while on a stint of a higher carb diet, I guess. Typically I hear about low carb putting somebody around the 90-110 area, if it gives them higher fasting blood glucose.

A few possibilities. One, sometimes a box of strips just sucks, I once had my fasting blood glucose testing near the prediabetic range, that lasted as long as that box of strips.

Another possibility is that his blood glucose was already running high. You don't really know if his fasting blood glucose is running higher on low carb--it might even be running lower than it was before low carb.

What are his postprandial blood sugars like? If a low carb meal doesn't move them that much, that's probably a good sign.