You’ve heard the terms “blood sugar” and “blood glucose”
but if you’re confused about why they matter, this guide can help.
What is blood glucose?
Blood glucose, also known as blood sugar, is one of the most important sources of
energy for your body. When you eat, food is broken down into basic nutrients: fats,
proteins, and carbohydrates. Carbohydrates — fiber, starch, and sugar — are broken
down into glucose or “blood sugar.”
Glucose is the only fuel used by brain cells except under extreme conditions like
starvation. Muscle cells use glucose during short bursts of activity like running
to your car in a rainstorm. Having good blood sugar balance is an important benchmark
of overall wellness because it prevents certain endocrine imbalances that can threaten
Glucose needs insulin to fuel your cells
Glucose circulating in your blood needs help to get into the cells. Insulin, a hormone
made by the pancreas, is the “key” that turns the “lock” (a cell’s insulin receptor)
to let glucose enter. When a cell is working hard — like a muscle cell rapidly expanding
and contracting during exercise — it needs more glucose for fuel. So the cell “summons”
insulin to bring in more glucose by increasing the number of insulin receptors on
its surface. Then insulin can increase the amount of glucose it has to offer the
cell as necessary.
Healthy glucose levels are a balancing act
Blood glucose rises and falls in a process called glucose homeostasis.
Blood glucose goes up after you eat carbohydrates but it can also increase in response
to stress, illness, or even excitement. Rising blood glucose signals the pancreas
to release more insulin so blood glucose levels stay in the healthy range. For people
without diabetes, that’s around 70 ng/dL (if they haven’t eaten for a while) to
about 120 ng/dL .
In addition to getting glucose from digesting carbohydrates, we have backup storage
we can turn to. Excess glucose from high-carb meals is converted into glycogen,
a complex sugar that’s kept in the liver or converted into fat to use if circulating
glucose runs low.
Your body also has a glucose “safety net” if blood glucose falls too low: the pancreas
releases glucagon, a hormone that tells the liver to open its energy
storehouse and release glycogen. Glycogen gets broken down into glucose and blood
Wonderfully, there’s also back-up for the back-up: fat. When glycogen stores are
full, the liver turns excess glucose into fatty acids for storage in fat cells.
If you are working really hard, and use up all the glucose as well as stored glycogen,
your body breaks down fat cells into glucose, fatty acids and byproducts called
ketone bodies. This generally keeps blood glucose levels high enough for your cells
to keep working.
What blood glucose testing levels mean
- Normal blood glucose is generally between 70 ng/dL (fasting) and up to 140 (after
- A fasting blood glucose of 100–119ng/dL means you’re at risk of type 2 diabetes.
- A fasting blood glucose ≥120 or Hemogloblin A1c >6.5% on two occasions, or a non-fasting
blood glucose >200, means you have type 2 diabetes.
The spectrum of potential blood sugar problems
Your body’s elegant glucose transfer-and-storage system can go wrong in a number
- Type 1 diabetes — the immune system sometimes mistakenly
attacks pancreatic cells, leaving the pancreas unable to produce insulin, and this
happens for various reasons. Without insulin, blood glucose rises to above-normal
levels (hyperglycemia).The cells starve without insulin because
there’s no way for glucose to get into them —unless insulin is injected. This is
also sometimes seen in advanced type II diabetes.
- Insulin resistance — the pancreas makes plenty of
insulin but cells stop responding to it. Since glucose can’t get into the cells,
it accumulates in the bloodstream. Researchers say insulin resistance is related
to several key factors including genetics, diet, exercise level, weight and lifestyle.
- Type 2 diabetes — if a person is insulin resistant
(which is primarily due to obesity, poor diet and low activity), the body signals
for more and more insulin to pour out of the pancreas to move glucose into the cells.
In the long term, this pathway becomes exhausted, and cells are less able to absorb
sugar. Eventually the body panics and behaves as if it’s starving. It breaks down
fat for energy but that creates a domino effect of elevated blood glucose (hyperglycemia)
and circulating fatty acids that end up promoting more insulin resistance. Meanwhile,
the excess glucose gets stored in fat cells, or worse, it’s excreted in the urine
(glucosuria) — and when that happens, you’ve got type 2 diabetes.
- Hypoglycemia (low blood sugar) — if insulin levels
get too high, blood glucose levels go down too fast, leaving you feeling weak, woozy,
cranky and craving carbs. Hypoglycemia is a very serious condition that can lead
to loss of consciousness.
- Inflammation — this immune system response to stress,
illness and toxins can raise blood sugar. If the body needs additional resources
to help the immune system, glucose is released by the liver and blood sugar rises.
This is fine in the short term but systemic, chronic inflammation degrades the body’s
insulin response and leads to bigger problems pretty quickly.
Best practices for healthy blood sugar: what to know about diet, weight and exercise
To have healthy blood sugar levels, you may need to make the following changes in
any, or all, of these three areas:
1. DIET Manage the number of simple carbohydrates
you eat every day to cut down on the glucose you’re taking in from food. Even people
with diabetes can (and should at certain times) eat some simple carbohydrates. Aim
to balance food groups and pair carbohydrates with protein, unsaturated fats, and
foods high in fiber like leafy greens.
2. WEIGHT Keep or find a healthy weight to tamp
down inflammation and to increase insulin sensitivity. While it can be very hard
to lose weight, find an easy-to-follow
plan that allows you to choose your favorite foods in each category. Then
you’ll be creating the conditions for steady, healthy weight loss. It’s very important
to not skip meals, especially breakfast. Regular meals are essential for maintaining
balanced glucose levels and reducing sugar cravings.
3. ACTIVITY LEVEL Exercise helps reduce both inflammation
and blood glucose, and makes cells more insulin sensitive. It also reduces stress
which helps prevent both inflammation and over-production of stress hormones that
raise blood glucose levels. Just 15 minutes can decrease blood glucose levels, even
in people with insulin resistance. Your goal should be at least 30 minutes of exercise,
5 days per week. If you exercise before or after a meal, it promotes better insulin
sensitivity and glucose usage to further stabilize your blood sugar.
Keeping your blood sugar within healthy limits is one of the most powerful steps
to prioritize so you feel your best and stay well. If you’re already dealing with
elevated blood sugar,
read our article and talk to your doctor about your next steps. You’re ready
to feel better and more energetic — aren’t you?
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