Blood Sugar Control

Insulin Schematic

Why your life depends on You!

The key to understanding blood sugar control is to understand the role played by special cells in your pancreas, called Beta-Cells. These tiny cells are scattered throughout your pancreas and their job is to produce insulin, store it, and release it into the blood stream at appropriate times.

The beta-cells of a healthy person who has not eaten in a while release a small amount of insulin into the blood stream throughout the day and night in the form of very small pulses every few minutes. This is called “basal insulin release.

Maintaining this steady supply of insulin is important. It allows the cells of the body to utilize blood sugar even if some time has passed since a meal.

The steady insulin level as another function, too. A dropping insulin level signals the liver that blood sugar is getting low and that it is time to add more glucose. When this happens, the liver converts the carbohydrate it has stored, (known as glycogen) into glucose, and dumps it into the blood stream. This raises the blood sugar back to its normal level.

Regular functioning of insulin

When a healthy person starts to eat a meal, the beta-cells kick into high gear. Their stored insulin is released immediately. Then, if the blood sugar concentration rises over 100 mg/dl, (5.5 mmol/L) the beta-cells start secreting more insulin into the blood stream. This early release of stored insulin after a meal is called “First Phase Insulin Release.” In a healthy person it keeps the blood sugar from rising to very high levels because it is available to meet most of the glucose that comes from the digestion of the current meal.
After completing the first phase insulin release, the beta-cells pause. Then, if blood sugar is still not back under 100 mg/dl (5.5 mmol/L), they push out another, smaller second phase insulin response which takes effect about an hour after the meal and, in a healthy person, brings the blood sugar back down to its starting level, usually by two hours after the start of a meal.

It is this combination of a robust first phase insulin response followed by a functional second phase insulin response that keeps the blood sugar of a normal person from ever rising over 140 mg/dl(7.8 mmol/L) even after a high carbohydrate meal.

When first phase release fails, or when second phase insulin response is sluggish, blood sugars start to rise to higher levels after a meal and take longer to return to normal. This condition is called “impaired glucose tolerance.” If the blood sugar rises over 200 mg/dl (11 mmol/L) after a meal the same condition is called “Diabetes.”

First and second phase insulin release may fail to do their jobs for several reasons. The most common is a condition called insulin resistance in which some receptors in the liver and the muscle cells stop responding properly to insulin. This means that though there is lots of insulin circulating in the body, the muscles and liver (but not, alas, the fat cells) don’t respond until the insulin levels rise much higher.

So when a person’s cells become insulin resistant, it will take a lot more insulin than usual to push circulating glucose into cells. Eventually the body may not be able to produce enough insulin to clear all the dietary carbohydrate from the bloodstream and blood sugars will rise to abnormal levels.

If your beta-cells are normal, and if insulin resistance at the muscles and liver is your only problem, over time you may be able to grow new pancreas islets filled with new beta-cells that can store even more insulin for use in first and second phase insulin response. In this case, though your blood sugar may continue to rise into the impaired range and take longer than normal to go back down to normal levels, your blood sugar response may never deteriorate past the impaired glucose tolerance stage to full-fledged diabetes. This is what happens to most people who have what is called “Metabolic Syndrome.” Unfortunately, if you have impaired glucose tolerance, there is no way of knowing if you fall into this group or if your rising blood sugars are caused by failing or dying beta-cells.

First phase insulin release also fails because beta-cells are dysfunctional or dying. This can happen along with insulin resistance, or without it. Studies have found that some thin, non-insulin resistant relatives of people with Type 2 Diabetes already show signs of beta cell dysfunction.

If beta-cells are dying or not working properly. The remaining beta-cells may be working full-time just to keep up with the need for a basal insulin release so they can’t store any excess in those granules for later release.

Scientists have discovered dozens of different genetic defects which cause beta-cells to fail or die in humans and animals. This means that one person’s Type 2 Diabetes can behave quite differently from that of another person, depending on what exactly is broken in their blood sugar control system. This is why drugs that work well for one person may do little for another person.

Whatever the reason for the failing first phase insulin release there’s an ugly feedback mechanism that kicks in when blood sugar levels rise because of that failing first phase insulin release: High levels of circulating glucose themselves are toxic to beta-cells, a phenomenon called “glucose toxicity”. So as blood sugars rise these high blood sugar concentrations further damage and or kill more beta-cells, making insulin release even less able to control blood sugar concentrations.

When first phase insulin release is weak or missing your blood sugar may easily rise over the 200 mg/dl (11 mmol/L) level currently defined as “diabetes.”

At that point, two bad things happen. When the concentration of glucose in your blood reaches 200 mg/dl (11 mmol/L) your cells become insulin resistant even if they weren’t insulin resistant before, so it takes a lot more insulin to lower your blood sugar from that point on.

And, even worse, the lack of a robust insulin response to the rising glucose may erroneously be interpreted by your liver as a sign that blood sugar is too low and that it is time to dump more glucose into the bloodstream. So in addition to the glucose coming in from your recent meal you also have to contend with additional glucose dumped by your poor old confused liver.

As you become more diabetic, and your second phase insulin response grows weaker, it may take four or five hours for your beta-cells to secrete enough insulin to bring your blood sugar level down to its fasting level. And, in fact, during the day your blood sugar may never get back to its fasting level because the glucose coming in from your next meal comes into the bloodstream before the glucose from the previous meal has completely cleared. Only at night, while you are sleeping, may your beta-cells finally secrete enough insulin to get your blood sugar down low enough that you wake up with a normal fasting blood sugar.

However, since it took all the insulin your beta-cells could make to get back to that normal blood sugar and they will have had no chance to store any extra insulin to take care of your breakfast. As soon as you throw that morning bagel down the hatch, blood glucose will rise, and once again your beta-cells will have to spend many hours trying to bring it back down.

Eventually, even the long hours of the night will not be enough time for your beta-cells to produce enough insulin to bring your blood sugar back to normal, and now, perhaps a decade after you achieved diabetic post-meal numbers, you will finally start seeing diabetic fasting blood sugar levels.

image – exploding-diabetes

This process explains why for many people who become diabetic–particularly middle-aged women, the fasting blood sugar level is the very last measurement to become abnormal. Only when a whole night isn’t long enough for your beta-cells to bring your blood sugar back down to normal or near-normal levels will you become diabetic by a fasting blood sugar test. That is why lately more emphasis is put on the measurement and control of post meal sugar control. It has been calculated that less then 40% of the people that have a  fpg <120 and HbA1C of 7 have post meal glucose <200mg/dl. This is a scary statistic considering the amount of diabetics that have worse data and consider themselves under good control!

People whose fasting blood sugar numbers have risen along with their post-meal numbers have generally lost more beta-cell function than those who still maintain normal or near-normal fasting blood sugars. This is why as soon as you discover that your post-meal blood sugars are rising beyond a normal level, it is so important to start controlling those abnormal post-meal blood sugars immediately. By doing so, you may be able to lower any insulin resistance, preserve your remaining beta-cells and keep your fasting blood sugar from ever deteriorating.

Even after you have been diagnosed as having a type 2 diabetic fasting plasma glucose, you may still have a good number of beta-cells left–anywhere from 40 to 60%. If you can reduce your insulin resistance through weight loss, exercise, and the use of drugs that counter insulin resistance, and if you keep your carb intake low to avoid blood sugar spiking, those cells may be able to produce enough insulin to control your blood sugar.

Even more important, if you keep your blood sugar under the damage-limit of 140 mg/dl (7.8 mmol/L) at all times, you may be able to keep glucotoxicity from murdering the rest of those cells.

Some studies mostly in cell-cultures and animal models have demonstrated that giving stressed beta-cells a rest can sometimes restore function. A few studies suggest this can also be done in humans.

One way of “resting” beta-cells is to use injected insulin as soon as type 2 diabetes is diagnosed, particularly if your blood sugars are very high at the time of diagnosis. If you take the burden off your beta-cells by supplementing insulin, there’s some suggestion that they may recover some of their ability to produce insulin later on so that you can go off insulin and retain much better control. You’ll still have to limit carbs and address any problems you have with insulin resistance through weight loss, exercise, and insulin-sensitizing drugs. But you’ll have an easier time doing it.

Every Tuesday and Thursday from 10 a.m. till noon, you can come to the Philipsburg Pharmacy for a free Diabetes and Blood-pressure check-up.