After being in ketosis more than a few weeks, and Thomas is being on a LCHFKD less than 30g, the type of ketones possibly spilled into the urine changes and may no longer register on a strip. The strips may be helpful for some at the start, but here is more info on the three types of ketones with reasons why they may/may not show up later on. http://forum.lowcarber.org/showthread.php?t=463436

Thomas, Glad to see you continue to do so well reducing your insulin dose! It must be rather tiny by now. Great that the VA system is supporting your goal to get off these meds and continue on your journey to good health. Just curious, do you have a Diabetes Educator there who advises (or at least doesn't oppose) a low carb approach to diabetes? You can continue to post here, or as before, feel free to join in any of the threads in the Diabetes forum or elsewhere.