TLDR: If your doing keto then you need to do a 3 day 150g/day carb refeeding before a OGTT to prime the pancreas to have a cache of insulin so that you can pass the test as a normal carb eater.

With the emergence of glycated hemoglobin as a diagnostic test for diabetes, oral glucose tolerance tests (OGTTs) have become rare in endocrinology practice. As they have moved out of favor, the importance of patient instructions on preparation prior to OGTT has faded from memory. Decades-old literature, well-known to endocrinologists a generation ago, emphasized the importance of carbohydrate intake prior to OGTT. In this expert endocrine consult, we discuss an OGTT performed in a research setting without adequate carbohydrate intake at the evening meal prior to the OGTT. The resultant elevated plasma glucose levels at 1-hour and 2-hours mimicked the loss of first-phase insulin release seen in early type 1 and type 2 diabetes. With clinical concern that the research participant had evolving type 1 or type 2 diabetes, the volunteer was subjected to additional testing and experienced anxiety. Repeat OGTT was normal after adequate carbohydrate intake (>150 grams/day and >50 grams the evening prior to overnight fast for the study). The physiology of this phenomenon is explored and is likely mediated through beta cell adaptation and alteration in peripheral glucose uptake in response to nutrient exposure. The learnings of decades ago have clearly faded, and this literature should be revisited to ensure that OGTT results are not compromised when ordered for clinical or research purposes.

Full Paper - https://doi.org/10.1210/jendso/bvab049

  • jet@hackertalks.comOPMEnglish
    2·
    2 months ago

    It’s a short case study, but the really interesting bit is the well referenced discussion with the authors lamenting the loss of knowledge as America has moved to a very carb heavy world, and that OGTTs become more and more rare.

    I want to be clear, this is NOT a demonstration of type 1 diabetes, its the body adapting to the normal metabolic environment and it can adapt right back the other way in 3 days.

    People claim to want metabolic flexibility, but what really matters is time under the curve of elevated blood glucose - so if you want to keep the pancreas primed with insulin you have to keep eating carbs… so even though the spike is lower the total area under elevation is larger.

    Well-and undernourished individuals who had normal glucose tolerance after a 5-day 300 gram carbohydrate preparatory diet were restricted to 20 grams carbohydrate for 5 days [2]. Restriction of carbohydrates resulted in delayed clearance of absorbed glucose in all individuals and was exaggerated in undernourished participants. After low-carbohydrate diets, all undernourished individuals met criteria for glucose intolerance or diabetes. Dr. Conn thus recommended a standard 300-gram carbohydrate diet prior to OGTT

    Unlike the primary beta cell defect observed in type 1 and type 2 diabetes, studies have demonstrated that the beta cell dysfunction caused by low-carbohydrate diets are likely reversible, as resumption of normal carbohydrate diet re-stores glucose homeostasis

    Hence the 3 day carb loading protocol working.

    Loss of expression of these proteins results in an insulin-resistance-like state, which is unlikely pathological, but instead an adaptation to consistently reduced glucose exposure

    The term insulin resistance is being used, but that isn’t true, the body is very insulin sensitive, even in the mice studies, its just the pancreas taking time to deliver the insulin to control blood glucose with a out of ordinary megadose of glucose

    Perhaps most importantly, as in the case presented here, OGTTs are increasingly used in research settings where in-vestigators may not be aware of the importance of proper preparation. Using the search terms oral glucose tolerance test or OGTT on clinicaltrials.gov on March 11, 2021, yielded >1500 studies that report OGTTs as part of the study protocol. As awareness of appropriate instruction prior to OGTT is lost and investigators less knowledgeable about the issues discussed here employ OGTTs, study out-comes and their volunteers may be impacted.

    THIS. So many studies say keto causes diabetes or insulin resistance because of this! They are wrong, and either out of ignorance or malice they are holding people back from better health.

    • At least 3 days of “unrestricted diet” (moderate- to high- carbohydrate intake), containing >150 grams of carbo- hydrates daily
    • Ideally, the meal plan should be delivered as 3 daily meals containing at least 50 grams of carbohydrates per meal
    • Perhaps most importantly, the last meal the evening be- fore the fasting test should include at least 50 grams of carbohydrates
    • Per WHO recommendations, “the test should be pre- ceded by an overnight fast of 10–16 hours during which water may be drunk”