I don't know if this will help, but here are my 2 cents. My personal experience with oatmeal (which I love) has been that when I eat oatmeal it raises my glucose higher than the same amount of carbs eaten in another form (such as bread) and that it also digests slower than other carbs, which affects the time when my glucose peaks. In fact, to not be high in the middle of the day after an oatmeal breakfast I have to skip lunch (I take regular in the AM, so I have insulin in me until about dinner, at which point I now switched to Humulog as R no longer is available in pen form). I have been a Type I for almost 40 years now and I have learned that all carbs are not the same. Also, you indicate you eat it with dried cranberries - what is the glucose level on those? That may also have an effect as dried fruits tend to be higher in fructose anyway, and if they have sugar on top of that your problem may be both the food you are eating, how your body reacts/digests it, and the mix/dose of insulins.
I don't have anything I can provide you regarding the lantus or Humulog (which I just started and which I am learning how my body reacts to, when to take, and how much to take right now).