Published on May 24, 2023
In this video, I am having a conversation with Dr. Penelope ‘Penny’ Figtree, a primar care physician from Port Macquarie on the East Coast of Australia. In her office, she is focussed heavily on using dietary approaches, particularly low-carb diets, to treat obesity, type 2 diabetes, and other metabolic diseases. She also has some unexpected personal experiences with blood sugar spikes, frequently also followed by episodes of reactive hypoglycemia.
In this video, we are discussing the value of continuous glucose monitors to identify which foods lead to blood sugar spikes and reactive hypoglycemia, how such spikes and the following low blood sugar levels can be avoided, and how regular spikes to just one food can even lead to a diagnosis of pre-diabetes if eats eaten regularly.
Connect with Dr. Penny Figtree
Low-Carb Port Macquarie. Dr. Figtree’s office: https://www.lowcarbpmq.com.au
On Facebook: https://www.facebook.com/groups/829022994702336
Twitter: https://twitter.com/PenelopeFigtree
References
- Wyatt et al.; Postprandial glycemic dips predict appetite and energy intake in healthy individuals. Nature Metabolism 2021; 3: 523-9.
- Norwitz et al.; Metabolic health immersion for medical education: a pilot program with continuous glucose monitors in medical and dental students. American Journal of Lifestyle Medicine 2022; ePub ahead of print August 15.
- Ludwig et al.; High glycemic index foods, overeating, and obesity. Pediatrics 1999; 103: e26.
- Summary of research on normal postprandial blood sugar levels vs. blood sugar spikes, and the impact of blood sugar spikes on chronic disease risks: blog post Blood Sugar Spikes – Q&A from May 10, 2023.
8 Responses
Critical question- I’m not diabetic nor am I pre-diabetic. But…
Was it the smoothie in general that spiked blood glucose or was it the ensure product in the smoothie?
I have a smoothie every morning for last 8 years. I don’t use any kind of powders, just ½ medium banana, ¼ blueberries, greek yogurt with fat, ¼ pear, oz or peanuts or freshly ground peanuts… those kind of ingredients. About 16oz typically but was thinking to reduce to 10oz.
My best guess is that it was the combination of lots of fruit in liquified form plus the starch and sugar from the protein drink. In general, I think people with glucose intolerance should be very careful with ‘liquid’ carbs. If you have this regularly, you may want to check a few times what your blood sugar does when you drink it. You can do this with a hand-held glucose meter as well, as long as you measure a few time points within the first 60-90 minutes after taking the first sip.
Cheers
Mario
I’ve lived with Reactive Hypoglycemia for the longest time. And I’m so familiar with the shakes and fainting and fuzzy-headedness that Dr. Figtree is talking about!
The way I identified it many years ago was through a Kraft Assay – which is a type of extended OGTT coupled with Insulin tests along the way. In India, when my lab runs an OGTT, blood sugar is tested at fasting, followed by a glucose load, and then blood sugar is tested every 30 minutes for either 2 hours or 4 hours, depending on the ask. When I added in the insulin test at each of those tests, I caught the massive insulin spike that leads to the Reactive Hypoglycemia I experience upon eating simple/naked carbohydrates.
Although Joseph Kraft never discussed this type of hyper insulin response, I find that it’s common. I’ve been wondering whether it’s a genetically wired hyper insulin response to carbohydrates or then caused by a learned response to insulin resistance. My HbA1c is 4.4%. Obviously because of the lows coupled with the low-carb approach I follow to prevent the lows! And to think I’m possibly headed towards more carbohydrate intolerance due my way of eating!
Hi Madhavi,
Thank you for sharing. It’s important to be clear that the Kraft test is not per se just a test of insulin resistance. For example, if someone has a lacking first-phase insulin response (check out my answer to question #6 in this video here https://youtu.be/LVw60RIhbzg if you haven’t seen it), then blood sugar would be expected to rise a lot immediately after eating, particularly after eating ‘naked’ carbs (as in an OGTT). That huge rise in blood sugar would then stimulate a more substantial second-phase insulin response, which may seem like insulin resistance, but that’s not necessarily the case. One would need to consider the rate of glucose disappearance in relation to the ambient insulin level, and if someone develops hypoglycemia in that second phase after a meal I’d say glucose disposal would have to be very good, and that would be indicative of very good insulin sensitivity.
A diminished first-phase insulin response is one of the earliest indicators of an increased risk of type 2 diabetes, and – by the way – is mostly genetically determined. Particularly among Asians, a genetic propensity to a diminished first-phase insulin response is often the key problem. See this paper here:
https://pubmed.ncbi.nlm.nih.gov/23704681/
Now note that being on a low-carb diet can also (temporarily) lead to a diminished first-phase insulin response. Because the first-phase insulin response is from pre-formed insulin, and why would the body keep insulin pre-formed in the beta-cells if never any carbs are eaten? So yes, being on a low-carb diet does make you more glucose intolerant due to a diminished first-phase insulin response, but by all accounts, this seems to be a temporary issue that can be reversed by eating carbs again.
Cheers
Mario
I happened across your interview with Dr. Penny Figtree and I am wondering if I am experiencing reactive hypoglycemia. I started wearing a CGM about a year ago because my A1C was climbing. It was 5.8 . I have been on a vegan diet for the past couple of years which has helped my symptoms of microscopic colitis. Lately however, I am watching for low blood sugar. For a couple of weeks when I woke up my blood sugar was in the 40’s, which was quite surprising and concerning. It would go up after breakfast but after lunch it is around 69-70. At that point I try to bring it up but honestly it is hard to figure out what to eat. Too much sugar and I have a blood sugar spike and then it seems the rest of the evening I am having to watch it often for another drop. I have tried eating 4-5 small meals a day just to keep things stable. I have added avocado and nuts to my meals but that hasn’t seemed to help. In the past I have been an avid exerciser but now just walking around the block drops the blood sugar to 70. I was just wondering if you could give me any suggestions as to how to eat so this wouldn’t happen or if you have any idea of what causes this. Thank you for your help.
Hi Cathy,
Unfortunately, it is difficult for me to give any guidance, because I cannot know enough about you from your comments. If your blood sugar levels are really in the 40s sometimes, you should see a doctor about this. You may want to confirm your CGM readings with a finger prick and hand-held glucose meter though; some CGM sensors are bad and show values that are way too low. Here are a few suggestions you could discuss with him or her:
– You could ask about checking on your general insulin and glucagon systems. Specifically, is there evidence that you hyper-secret insulin? This doesn’t have to be the case, but if glucose levels often are this low, this is good to check on and rule out.
– Considering your other medical history, would it be OK to incorporate more protein? Including a large serving of protein in a meal, and ideally eating fiber-rich veggies or salad and a portion of protein first, and complex, low-glycemic index carbs later in the meal should be possible without triggering a spike, unless you are glucose intolerant (which the doctor can also check on).
– Be clear that a blood sugar spike, as I define it, is an increase in blood sugar to 180 mg/dL (10 mmol/L) or higher. Many people on social media define spikes as a little bump in blood sugar from 90 to 120 mg/dL after a meal, which I don’t think is anything to worry about.
Best wishes,
Mario
Fascinating interview with Dr. Figtree. I’d heard about reactive hypoglycemia but didn’t really understand it. I am one of those people who can spike up to at least 180 – maybe more. I have learned this by using a CGM off and on for the last year. It happens within an hour and comes right back down but just to where I started. Not lower. Using a CGM has been an interesting adventure. I tried Nutrisense and I liked the way I could set the range from 70-140. But I got a deal with Levels and have been using that but here is what they say “Based on the data of healthy individuals wearing CGM, it appears that it is safe and healthy to strive for a fasting glucose between 72-85 mg/dL, a post-meal glucose level of 110 mg/dL or lower, and an average glucose of 100 mg/dL or lower.” In order to achieve that I would have to go very low carb which isn’t really what I want. I have read all your blogs now and had already tried the various “hacks” which do help me to stay in the 70-140 range. I am in that range 97% of the time. The one I didn’t know about was about the 2nd meal effect. I think by trying to keep my range low but not being consistent – that really didn’t help. That is why I appreciate your information so much. I find it more reasonable and achievable. I don’t think I’m insulin resistant – fasting insulin is 3.0. My fasting glucose was 111 last year and according to recent HbA1c of 5.6 would be around 114, though my CGM says my average for the last 2 weeks is 96. But any of those still gives a low HOMA-IR. I also never have lower than 70 glucose. It appears there are some things that I have to really manage: bread, rice, bananas. And one reason I have tried to make sure I get more carbs and stay in a range under 140 vs. 110 is that I have lost weight that I really didn’t need to lose. In a year since I started the CGM I have dropped from 134 to 115 – I’m 5’4″ and really don’t want to lose more weight. I am trying to stick to healthy fats though I do eat meat, eggs, kefir. From what I understand snacks are maybe not that good so I don’t think that is a way to keep my weight up. I also get a fair amount of exercise – usually a good 1 hour walk each day with some elevation gain. Is there any advice you can offer as far as diet is concerned? Does it sound like I am on the right track?
Hi,
Thank you for your comment. You raise many good points, and most will be addressed in the videos I will publish this year (in a series called ‘preventing and reversing insulin resistance’).
Regarding the optimal blood glucose ranges set by Levels, I do not agree with them, as I see no evidence that such much lower levels are associated with a lower risk of chronic disease when compared to the thresholds I suggest. And that is all other things being equal, which also isn’t the case because in order to flatten your glucose curve so much, you would have to go low-carb, which carries other disadvantages, at least potentially.
Cheers
Mario