Some mixed thoughts on blood sugar, both the "long" and "short" term.
Hemoglobin A1c (HbA1c)/Long-term blood sugar/"Tattletale"
Dear child has many names......
HbA1c is, in simple terms, the amount of glucose that has stuck to the red blood cells, thus reflecting the average blood sugar one has had in the lifespan of red blood cells (the last 90-120 days). Doctors measure HbA1c and often treat based solely on this number. In my opinion, it's not a particularly good marker to treat by, as a satisfactory HbA1c can conceal some very unhealthy blood sugar variations with high peaks and deep valleys, which can be very taxing on the body's cells and organs. HbA1c itself is not to blame for complications, as it's the daily blood sugars that, combined, create HbA1c, which also generate any complications. Both consistently high blood sugar and highly variable blood sugar can be harmful to health and lead to various complications. The latter is likely the worst, and it's not always captured in the measurement of HbA1c.
HbA1c as a diagnostic tool
Previously, fasting blood sugar and oral glucose tolerance tests were used to diagnose diabetes, but in 2010, HbA1c was implemented as the new diagnostic tool. If HbA1c is 48 mmol/mol or higher, one has diabetes. In my personal opinion, 48 mmol/mol is too high a threshold. This figure was decided upon because retinopathy (diabetic eye disease) develops from there, but it turns out that complications can arise long before, such as neuropathy (nerve damage). So, the threshold of 48 mmol/mol should be lowered to about 45 mmol/mol, in my opinion.
The 48 mmol/mol is a decided threshold taken by some professional experts, but it's not based on exact analyses, research, etc. - just a decided consensus. It's time to take a closer look at this threshold. One has been insulin resistant for probably several years before HbA1c reaches 48 mmol/mol or higher, and thus, one has had elevated insulin levels in the blood for a long time, which is at least as harmful as elevated blood sugar. Doctors should measure insulin levels when there's the slightest suspicion of risk for pre- or diabetes. This measurement (c peptide) can indicate risk long before HbA1c shows up, and catching many more cases in the bud, thus avoiding actual diagnoses.
Daily blood sugars
Food and drink intake affect blood sugar, but to varying degrees.
Carbohydrates affect blood sugar levels significantly.
Protein affects blood sugar levels somewhat.
Fat affects blood sugar levels minimally.
Therefore, there is good reason not to consume too many absorbable carbohydrates, regardless of whether they are so-called fast or slow. My experience is that there is not much difference in the speed of carbohydrate absorption. My blood sugar almost always peaks 45-60 minutes after eating, regardless of the type of carbohydrates. Carbohydrates are sugar molecules linked together in varying chain lengths, which just need to be "cut" before ending up as glucose in the blood. This cleaving process starts in the mouth when food mixes with saliva and its amylase. An exception is dietary fibers, which are also carbohydrates but are hardly absorbable and therefore do not affect blood sugar.
A good example of so-called slow and healthy carbohydrates is this small test of 130 grams of whole grain bread (multigrain roll), which is recommended as being healthy and good even for diabetics!
As the graph shows, measured with CGM (Freestyle Libre), my blood sugar rose quickly and high, and it doesn't quite resemble slow or healthy carbohydrates! I have tested oatmeal several times, and it's exactly the same picture. The idea that diabetics can eat whole grain products without issues is unfortunately completely off the mark.
Increasing blood sugar under unusual circumstances
Blood sugar often rises late at night or just upon waking up. This is called the Dawn Phenomenon. It's the body's way of preparing for the day's activities, historically gearing up for "flight or fight" right from the morning. Certain hormones prompt the liver to release glucose from its glycogen stores so the muscles can have energy for increased activity after sleep. Blood sugar typically doesn't drop until after eating, as the pancreas releases insulin in response to food.
During and immediately after exercise, blood sugar can also rise. It's essentially the same mechanism as described above during the Dawn Phenomenon. Muscles require extra energy, so the liver releases extra glucose into the bloodstream. During exercise, muscles often use this extra glucose without the need for insulin, solely through a glucose transporter (glut4). When exercise stops, muscles no longer require as much energy, but there is glucose on its way from the liver and in the blood, hence the rise in blood sugar just after exercise. There's no danger in this. The pancreas just needs a moment to release some insulin to lower it, which happens shortly after.
Under other forms of bodily stress, such as heat or cold baths, infections, illness, and fasting, the same often occurs. Blood sugar rises because the body prepares "for battle" in response to something abnormal. There's nothing dangerous about these blood sugar increases because it's only about 1 gram of extra glucose, which the body doesn't perceive as harmful, so it doesn't lower it with insulin.
For example, blood sugar in the morning might rise by perhaps 3 mmol/l based on this single gram of extra glucose, whereas it rises roughly the same if you consume 30 grams of glucose in the form of starch (such as oatmeal) because the latter triggers a strong insulin response and keeps it down. There's, of course, a big difference in the body's response to the two scenarios, and the first is clearly less harmful than the latter. High insulin levels increase insulin resistance, create inflammations, increase small oxidized LDL particles, and other unhealthy conditions in the body.
The conclusion is that many factors affect blood sugar, and some of these increases almost happen automatically. However, the most harmful of them can fortunately be avoided/kept down by eating and drinking healthily and without too many carbohydrates, provided that you still have a satisfactory insulin production, which most type 2 diabetics have for many years after diagnosis.
The point of my post is mainly that learning, knowledge, and experience about this somewhat troublesome disease make it much easier to manage when you know where to focus your efforts.
Feel free to provide comments and disagreements, if any.
PS: I completely forgot to give an update on the physical challenges that I always present to myself and my body to keep it active. Since last time, I went on a trip to Tromsø, Norway to see the Northern Lights, which was achieved already on the first evening-night. It was the most beautiful Northern Lights seen out in the wilderness far from the city.
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