Your body breaks down every carb you ingest into glucose, also known as blood sugar because it travels through your bloodstream.[1] Glucose is a simple sugar — more precisely, a monosaccharide (mono meaning single and saccharide meaning sugar). To store glucose, your body combines the molecules into a polysaccharide (poly meaning several) called glycogen, which gets stored in your liver and muscles.
Insulin (a hormone produced by your pancreas) rises when blood glucose rises;[2] it lowers blood sugar by telling various cells to absorb it — for storage in your liver or muscles or for immediate use — and your liver to stop producing new glucose.[3]
The ability of cells to absorb glucose in response to insulin is called insulin sensitivity, and low insulin sensitivity is called insulin resistance. The more sensitive you are to insulin, the less resistant, and vice versa.
It is also possible to produce too little insulin. If you have type 1 diabetes or are in the late stages of type 2 diabetes, in which case you suffer from insulin deficiency, glucose can’t be removed efficiently from your blood, causing hyperglycemia (overly high glucose levels).[4]
Insulin resistance paves the way for type 2 diabetes, which can cause your blood sugar levels to consistently remain too high for too long. If not managed, these high blood sugar levels can lead to serious health complications — mostly cardiovascular diseases,[5] but probably cancer, Alzheimer’s, and Parkinson’s as well.[6][7][8]
What are the symptoms of abnormal blood glucose levels?
Symptoms of abnormal glucose levels are different from person to person and may not even be present until the levels are very high or very low. Generally, blood sugar symptoms may show up when levels fall below 70 mg/dL (3.9 mmol/L) or over 180 mg/dL (10 mmol/L).
What affects blood glucose?
Diets & foods
Across numerous observational studies, grains, vegetables, fruits, and dairy have been consistently associated with decreasing the risk of type 2 diabetes.[13]
Multiple randomized controlled trials (RCTs) have come to similar conclusions.[14]
Nuts, grains, legumes, and dairy provided the greatest fasting blood sugar reductions.
Grains, legumes, nuts, fish, fruits, and vegetables improved HOMA-IR (a measure of insulin sensitivity) the most.
Grains, legumes, fruits, vegetables, and nuts provided the greatest blood sugar reductions in HbA1c tests.
Listed from most to less potent, grains, nuts, legumes, fruits, and vegetables had the greatest impact on improving overall blood sugar control.
Lifestyle
The major cause of abnormally high blood glucose is excess calorie intake and the resulting increase in fat mass. Unsurprisingly, weight loss can help. One review found that weight loss from all kinds of interventions — surgery, appetite-suppressing medicines, lifestyle interventions, or a combination — alleviates diabetes.[15]
Surprisingly, many long-term studies that used diet alone to achieve weight loss reported only modest improvements in diabetes, probably because few achieved substantial long-term weight loss.[16] Moreover, exercise in itself can help reduce the risk and severity of type 2 diabetes.[17][18][19]
Exercising regularly and maintaining a healthy weight are the two major pillars of metabolic health, but insulin resistance can be complex. As a result, the basics may not always cut it, and what’s effective for one person may not be for another. Unfortunately, researchers are often unable to explore differences between individuals, leaving diabetics to fight their disease through trial and error based on what’s effective for the majority.
Medical conditions & considerations
Stress, illness, physical trauma, and dehydration can do some strange things to your blood sugar levels. Menstrual cycles and pregnancy may also throw off your blood sugar.
Injury to the pancreas, where insulin is produced, can lead to hyperglycemia, as can hormone disorders such as Cushing’s syndrome (excess cortisol in the body), pheochromocytoma (a usually benign tumor in an adrenal gland), hyperthyroidism (high thyroid levels), and acromegaly (excess growth hormone that causes abnormally large features).
Drugs
Insulin is perhaps the most well-known and widely used drug to regulate blood sugar levels. But even commonly consumed legal drugs, such as alcohol and caffeine, can have an effect.
Read more about it here: https://examine.com/topics/blood-glucose/