Blood(y) Glucose — Ups & Downs

Before I came to Perfood, I didn’t pay much attention to my blood sugar. But since I am now confronted with questions about blood sugar on a daily basis, I am fascinated by how strongly supposedly small snacks affect my actually healthy body and how weakly some main meals influence blood sugar.
During my last MillionFriends test phase, I noticed that my blood sugar not only goes up and down to different degrees, but also sometimes goes in waves. Let me briefly explain the background: in the 2–3 hours after a meal, it is metabolised in the body, i.e. digested and processed. The nutrients are broken down in the gastrointestinal tract and then absorbed through the intestinal wall.

Carbohydrates also enter the blood in this way — the blood sugar rises. Insulin is now released and helps to absorb the blood sugar from the cells, the blood sugar drops. The digestion of a meal and the subsequent insulin response take about 2h, sometimes a little longer. “I know that,” you say? “That’s the blue curve below.”
Right!

(aus Cheng et al. 2019)

And why am I showing you another red one and a green one and what do they mean? And: are they good or bad? I asked myself the questions because I get the m-shaped curve shown in green relatively often.
But let’s take it one step at a time:
The blue curve is called “monophasic”, which means it has one peak at the top. The red curve has two peaks, one up and one down, that’s why it’s called biphasic. And the green curve has three peaks, so it’s triphasic (Cheng et al. 2019).

It has been shown in studies with healthy subjects that monophasic curves indicate that individuals have lower metabolic health than those who had biphasic or triphasic blood glucose curves (de Andrade Mesquita et al. 2018). Metabolic health is defined by insulin sensitivity, which is how well cells respond to insulin and thereby take up glucose. This means that if someone has low metabolic health, their insulin sensitivity is lower than normal. As a result, glucose is absorbed more slowly and the sugar stays in the blood longer. You can see this in the blue curve — blood glucose rises sharply and falls slowly because insulin has to work harder to get it into the cells.
The same thing has been seen in overweight but healthy, pre-diabetic and diabetic people (Kim et al. 2016; Cheng et al. 2019; Nolfe et al. 2012). Those with bi- or triphasic curves had higher insulin sensitivity, lower BMI and better blood glucose levels in all studies. Interestingly, those with the triphasic curves were even slightly healthier. So it’s a good sign if you have bi- or triphasic glucose curves, as strange as they look at first glance.
One theory for these blood glucose responses has currently gained acceptance: When a metabolically healthy person ingests carbohydrates, the body produces insulin relatively quickly in the pancreas so that the sugar can be absorbed from the blood. This is because sugar in higher concentrations should only be in the blood for as short a time as possible. But in order not to produce too much insulin, the body then waits and first checks how much carbohydrate is actually being eaten. You can see this in the first upward curve of the bi- and triphasic curves. The green and red curves, however, do not rise as high as the blue curve. This is because metabolically less healthy people either produce less insulin or the insulin is less effective, so that the glucose cannot be absorbed as quickly and remains in the blood for longer.

People with biphasic curves have a faster drop in blood glucose, which then rises again because the body waits to see how much carbohydrate is actually coming in and then releases insulin again as needed. In people with triphasic curves, the cells react even better to insulin, so that the sugar is absorbed from the blood even more quickly and falls off. This is then followed by uptake from the gut again, blood sugar rises and the insulin produced and well causes a healthy drop again (Arslanian et al. 2019; de Andrade Mesquita et al. 2018).

Knots in your head? Take another look at the picture above and then read the text again at your leisure. Keep in mind that this theory probably also depends on how quickly the stomach empties, how well it was chewed and what carbohydrates were eaten.
Metabolic health is important and can be regained. So you don’t have to worry if your curves are always monophasic — there’s still a lot you can do with healthy eating and weight loss! And flat blood glucose curves are ideal anyway, showing so little deflection that you can hardly distinguish between mono-, bi- and triphasic curves. With MillionFriends you can find such a diet for yourself.

Got hooked? Here you can find more scientific information on the topic:

Andrade Mesquita, Leonardo de, Luciana Pavan Antoniolli, Giordano Fabricio Cittolin-Santos, and Fernando Gerchman. 2018. “Distinct Metabolic Profile According to the Shape of the Oral Glucose Tolerance Test Curve Is Related to Whole Glucose Excursion: A Cross-Sectional Study.” BMC Endocrine Disorders 18 (August): 56. https://doi.org/10.1186/s12902-018-0286-7.

Arslanian, Silva, Laure El ghormli, Joon Young Kim, Fida Bacha, Christine Chan, Heba M. Ismail, Lorraine E. Levitt Katz, Lynne Levitsky, Jeanie B. Tryggestad, and Neil H. White. 2019. “The Shape of the Glucose Response Curve During an Oral Glucose Tolerance Test: Forerunner of Heightened Glycemic Failure Rates and Accelerated Decline in β-Cell Function in TODAY.” Diabetes Care 42 (1): 164–72. https://doi.org/10.2337/dc18-1122.

Cheng, Xinqi, Na Yang, Yuxiu li, Qi Sun, Ling Qiu, Lingling Xu, Fan Ping, Wei Li, and Hua-Bing Zhang. 2019. “The Shape of the Glucose Response Curve during an Oral Glucose Tolerance Test Heralds β-Cell Function in a Large Chinese Population.” BMC Endocrine Disorders 19 (November). https://doi.org/10.1186/s12902-019-0446-4.

Kim, Joon Young, Sara F. Michaliszyn, Alexis Nasr, SoJung Lee, Hala Tfayli, Tamara Hannon, Kara S. Hughan, Fida Bacha, and Silva Arslanian. 2016. “The Shape of the Glucose Response Curve During an Oral Glucose Tolerance Test Heralds Biomarkers of Type 2 Diabetes Risk in Obese Youth.” Diabetes Care 39 (8): 1431–39. https://doi.org/10.2337/dc16-0352.

Nolfe, Giuseppe, Maria Rita Spreghini, Rita Wietrzycowska Sforza, Giuseppe Morino, and Melania Manco. 2012. “Beyond the Morphology of the Glucose Curve Following an Oral Glucose Tolerance Test in Obese Youth.” European Journal of Endocrinology 166 (1): 107–14. https://doi.org/10.1530/EJE-11-0827