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Diabetes. We can help in most cases.
Understanding How Insulin Regulates Blood Glucose
Professor Christopher D. Saudek, M.D. explains the path of glucose in diabetes.
In someone with diabetes, the body’s ability to secrete insulin -- and the counter-regulatory hormone
glucagon -- is impaired. The pancreas is an elongated organ that extends across the abdomen, below
the stomach. In addition to secreting certain enzymes that aid in food digestion, the pancreas also
manufactures hormones responsible for regulating blood glucose levels.
Scattered throughout the pancreas are more than a million tiny nests of cells known as the islets of
Langerhans. Each islet contains several different types of cells. The majority are beta cells, which
produce and store the hormone insulin until it is needed. Also located in the islets are alpha cells, which
make and store glucagon, a hormone that counteracts the effects of insulin.
After a meal, carbohydrates are broken down into smaller molecules as food travels through your
digestive tract. Complex carbohydrates (found in starchy foods, such as pasta and potatoes) are long
strings of glucose that require more digestion than simple sugars (such as sucrose in candy or table
sugar). Digestion begins in the mouth. A salivary enzyme called amylase breaks down carbohydrates
into smaller molecules that pass through the esophagus and stomach and into the small intestine.
Another type of amylase from the pancreas and enzymes in the intestine then split the partially digested
carbohydrates into simple sugar molecules small enough to be absorbed across the intestinal wall.
The absorbed glucose and other simple sugars then travel to the liver via the portal vein. Once there,
the simple sugars are converted into glucose in the liver, which in turn releases glucose into the
bloodstream according to how much your body needs for energy. Some of the unused glucose is stored
in the liver and muscle tissue as glycogen for future energy needs and the rest is stored as triglycerides
in adipose (fatty) tissue.
After you eat a meal that contains carbohydrates and glucose enters the bloodstream, it triggers a
response by the pancreas and causes the cells in the islets of Langerhans within the pancreas to
produce and release insulin. The insulin, in turn, allows glucose to move from the bloodstream into the
cells in your body, where it is used for energy.
If you have type 1 diabetes, the pancreas produces little or no insulin, and glucose remains in
the bloodstream instead of entering cells. If you have type 2 diabetes, the pancreas produces and
releases insulin, but the cells are not sensitive enough to it and insufficient glucose enters the cells. The
glucose remaining in the bloodstream signals the pancreas to produce even more insulin. Eventually,
however, the pancreas is not able to produce enough insulin to overcome the reduced responsiveness
of cells to insulin.
To recap:
In someone without diabetes, beta cells sense the rising blood glucose levels and secrete
insulin into the blood. Once in the bloodstream, insulin helps glucose enter the body’s cells,
where it is “burned” for energy or converted to glycogen by the liver and muscles and stored
there for future energy needs. As a result, blood glucose levels return to normal, and insulin
secretion decreases.
On the other hand, a drop in blood glucose levels - for example, when one hasn’t eaten for
several hours -- stimulates the alpha cells to secrete glucagon into the blood. Glucagon
raises blood glucose levels by signaling the liver to convert stored glycogen back into
glucose and release it into the bloodstream. Normally, the secretion of these hormones by
the pancreas is perfectly balanced: Beta and alpha cells continuously monitor blood glucose
levels and release insulin or glucagon as needed.
But in someone with diabetes, this delicate balance is impaired because the beta cells produce little or
no insulin, the body’s cells are resistant to insulin, or a combination of both is at work. Regardless,
glucose cannot enter cells effectively and remains in the bloodstream. The result is persistently high
blood glucose levels (hyperglycemia). Without treatment, hyperglycemia can lead to serious long-term
complications, such as heart, eye, and kidney disease.
Type 2 diabetes usually develops gradually over many years and the initial symptoms may be
almost unnoticeable. In fact, many people find out that they have type 2 diabetes when a routine
laboratory test shows high blood glucose levels. Increasingly endocrinologists are using the hemoglobin
A1c (HbA1c) test -- which is now used to monitor glucose control in existing patients -- to diagnose
diabetes.
If you have any of the common symptoms that suggest the presence of diabetes, your doctor can order
a blood glucose test to confirm or rule out the diagnosis. Three blood tests commonly used to diagnose
prediabetes and diabetes:
casual plasma (blood) glucose
fasting plasma glucose (FPG)
oral glucose tolerance test (OGTT)
Blood glucose levels naturally fluctuate, so don't get exceptionally worried if they go up for no apparent
reason -- we can never explain every rise and fall. Food and drink, stress or an illness can also provoke
a temporary jump, and a cortisone injection (into a knee or shoulder, for instance) will predictably raise
blood glucose a lot.
Your average blood glucose level (HbA1c) is the best indication of how well you are managing your
diabetes over time. That doesn't mean you shouldn't monitor your blood glucose levels at various points
in the day. Finger-stick tests can give an early indication that your glucose is rising faster than it should.
The HbA1c test measures the amount of glucose attached to hemoglobin -- the oxygen-carrying protein
in red blood cells that gives blood its color. As blood glucose levels rise, so does the amount of glucose
attached to hemoglobin. Since hemoglobin circulates in the blood until the red blood cells die (half of red
blood cells are replaced every 120 days), the HbA1c test measures average blood glucose levels over
the previous two to three months.
The American Diabetes Association recommends keeping your HbA1c levels at less than 7%, which is
equivalent to an average blood glucose level of about 170 mg/dL or less.
HbA1c tests are usually performed every three months to see if you are maintaining your blood glucose
within the target range. If you have stable blood glucose levels and are meeting your treatment goals,
you may need less frequent HbA1c testing.
Keep in mind that blood glucose naturally goes up and down, and sometimes the fluctuations are
unpredictable. No matter how hard you try, your levels will not be normal every time you test. As long as
they don't stay too high, you should be in good shape.
To make an appointment with Doctor Maya
Professor Christopher D. Saudek, M.D. explains the path of glucose in diabetes.
In someone with diabetes, the body’s ability to secrete insulin -- and the counter-regulatory hormone
glucagon -- is impaired. The pancreas is an elongated organ that extends across the abdomen, below
the stomach. In addition to secreting certain enzymes that aid in food digestion, the pancreas also
manufactures hormones responsible for regulating blood glucose levels.
Scattered throughout the pancreas are more than a million tiny nests of cells known as the islets of
Langerhans. Each islet contains several different types of cells. The majority are beta cells, which
produce and store the hormone insulin until it is needed. Also located in the islets are alpha cells, which
make and store glucagon, a hormone that counteracts the effects of insulin.
After a meal, carbohydrates are broken down into smaller molecules as food travels through your
digestive tract. Complex carbohydrates (found in starchy foods, such as pasta and potatoes) are long
strings of glucose that require more digestion than simple sugars (such as sucrose in candy or table
sugar). Digestion begins in the mouth. A salivary enzyme called amylase breaks down carbohydrates
into smaller molecules that pass through the esophagus and stomach and into the small intestine.
Another type of amylase from the pancreas and enzymes in the intestine then split the partially digested
carbohydrates into simple sugar molecules small enough to be absorbed across the intestinal wall.
The absorbed glucose and other simple sugars then travel to the liver via the portal vein. Once there,
the simple sugars are converted into glucose in the liver, which in turn releases glucose into the
bloodstream according to how much your body needs for energy. Some of the unused glucose is stored
in the liver and muscle tissue as glycogen for future energy needs and the rest is stored as triglycerides
in adipose (fatty) tissue.
After you eat a meal that contains carbohydrates and glucose enters the bloodstream, it triggers a
response by the pancreas and causes the cells in the islets of Langerhans within the pancreas to
produce and release insulin. The insulin, in turn, allows glucose to move from the bloodstream into the
cells in your body, where it is used for energy.
If you have type 1 diabetes, the pancreas produces little or no insulin, and glucose remains in
the bloodstream instead of entering cells. If you have type 2 diabetes, the pancreas produces and
releases insulin, but the cells are not sensitive enough to it and insufficient glucose enters the cells. The
glucose remaining in the bloodstream signals the pancreas to produce even more insulin. Eventually,
however, the pancreas is not able to produce enough insulin to overcome the reduced responsiveness
of cells to insulin.
To recap:
In someone without diabetes, beta cells sense the rising blood glucose levels and secrete
insulin into the blood. Once in the bloodstream, insulin helps glucose enter the body’s cells,
where it is “burned” for energy or converted to glycogen by the liver and muscles and stored
there for future energy needs. As a result, blood glucose levels return to normal, and insulin
secretion decreases.
On the other hand, a drop in blood glucose levels - for example, when one hasn’t eaten for
several hours -- stimulates the alpha cells to secrete glucagon into the blood. Glucagon
raises blood glucose levels by signaling the liver to convert stored glycogen back into
glucose and release it into the bloodstream. Normally, the secretion of these hormones by
the pancreas is perfectly balanced: Beta and alpha cells continuously monitor blood glucose
levels and release insulin or glucagon as needed.
But in someone with diabetes, this delicate balance is impaired because the beta cells produce little or
no insulin, the body’s cells are resistant to insulin, or a combination of both is at work. Regardless,
glucose cannot enter cells effectively and remains in the bloodstream. The result is persistently high
blood glucose levels (hyperglycemia). Without treatment, hyperglycemia can lead to serious long-term
complications, such as heart, eye, and kidney disease.
Type 2 diabetes usually develops gradually over many years and the initial symptoms may be
almost unnoticeable. In fact, many people find out that they have type 2 diabetes when a routine
laboratory test shows high blood glucose levels. Increasingly endocrinologists are using the hemoglobin
A1c (HbA1c) test -- which is now used to monitor glucose control in existing patients -- to diagnose
diabetes.
If you have any of the common symptoms that suggest the presence of diabetes, your doctor can order
a blood glucose test to confirm or rule out the diagnosis. Three blood tests commonly used to diagnose
prediabetes and diabetes:
casual plasma (blood) glucose
fasting plasma glucose (FPG)
oral glucose tolerance test (OGTT)
Blood glucose levels naturally fluctuate, so don't get exceptionally worried if they go up for no apparent
reason -- we can never explain every rise and fall. Food and drink, stress or an illness can also provoke
a temporary jump, and a cortisone injection (into a knee or shoulder, for instance) will predictably raise
blood glucose a lot.
Your average blood glucose level (HbA1c) is the best indication of how well you are managing your
diabetes over time. That doesn't mean you shouldn't monitor your blood glucose levels at various points
in the day. Finger-stick tests can give an early indication that your glucose is rising faster than it should.
The HbA1c test measures the amount of glucose attached to hemoglobin -- the oxygen-carrying protein
in red blood cells that gives blood its color. As blood glucose levels rise, so does the amount of glucose
attached to hemoglobin. Since hemoglobin circulates in the blood until the red blood cells die (half of red
blood cells are replaced every 120 days), the HbA1c test measures average blood glucose levels over
the previous two to three months.
The American Diabetes Association recommends keeping your HbA1c levels at less than 7%, which is
equivalent to an average blood glucose level of about 170 mg/dL or less.
HbA1c tests are usually performed every three months to see if you are maintaining your blood glucose
within the target range. If you have stable blood glucose levels and are meeting your treatment goals,
you may need less frequent HbA1c testing.
Keep in mind that blood glucose naturally goes up and down, and sometimes the fluctuations are
unpredictable. No matter how hard you try, your levels will not be normal every time you test. As long as
they don't stay too high, you should be in good shape.
To make an appointment with Doctor Maya