With careful monitoring, the right therapy, and a healthy lifestyle, people with type 1 can remain healthy and free of major complication well into later life.

Blood Sugar Targets

Well-known diabetes consultant Carolyn Robertson offers this advice. “I think aiming for a fasting blood sugar of 70 mg/dL is too low unless you are pregnant. I recommend a range of 100–140 fasting/pre-meal and 120–180 post-meal.”

Monitoring & Self-Management

Living well with type 1 is like perpetually solving a puzzle with pieces that are continually morphing. The main pieces are insulin, food and exercise, and blood-glucose testing.

Fundamentally, your challenge is trying to approximate the healthy metabolism of a person without the disease—that is, keeping blood glucose levels within a near-normal range as much of the time as possible, waking or sleeping. Most people never need to think about how their body releases insulin in response to what they’ve just eaten, or how many carbs that food contained, or whether a trip to the gym might tip the balance into low blood sugar. But for those with type 1, monitoring, testing, counting, and calculating are facts of daily life.

As these skills become second nature, staying healthy is more assured. And looking down the road, you’re more likely to avoid the common complications of type 1. Not that it’s ever truly easy, even with the latest technology of pumps and glucose monitoring devices. No one manages to keep blood glucose in the normal range all the time. Aside from inevitable human error or occasional flings, other health factors or environmental stresses enter the picture now and then. If you have a bad day, try to understand what went wrong, forgive yourself, and take action to improve things.

Checking Blood Sugar

Good management starts with blood-glucose monitoring, and in monitoring, the watchword is “often.”  Remember, the nondiabetic’s system automatically “checks” blood sugar every few minutes and uses that information to gauge the insulin response. Before meals, after meals, during “fasting” periods, and even at random times during the day—all are important. Changes in life patterns such as travel or illness may calls for checking at other times or intervals.

Monitoring blood sugar guides you, in the short term, on how to calibrate your insulin use, your food intake, and your physical activity. All are intimately interwoven.

In the longer term, the data you record from blood glucose measurements reveal how you’re doing at managing the disease overall. There are two important long-range methods of checking your blood sugar control. They are:

  • Frequent measuring of blood glucose. Typically people strive to keep fasting blood sugars under 140 mg/dL. Some try for a range of 70 to 120 mg/dL fasting; for others the effort to avoid low blood sugar and frequent swings dictate a wider range of 90 to 180 mg/dL. The frequency of checking should be at least 4 times daily—before each meal and at bedtime. More frequent monitoring allows you to fine-tune responses. Some health-care professionals want the diabetic to test blood sugar in the middle of the night to assess what the blood sugar is doing overnight.
  • Periodic measurement of glycosylated hemoglobin. Another method to monitor the control of blood sugar is through a blood test called hemoglobin A1c or glycohemoglobin (or glycosylated hemoglobin). This test can be done through a lab or a doctor's office, and has recently become available for testing at home. Hemoglobin A1c tells the average of what blood sugar levels have been running for the past 3 months. It does not reveal how you are doing moment to moment.

What’s the best way to measure?

Some background: It’s long been accepted wisdom that the A1c test is the best guideline of effective blood sugar management. To summarize: An HbA1c of 6% or less is normal. Values for people with diabetes are 6.5% or higher; those with diabetes (type 1 or 2) are advised to keep their level at or below 7%.  This is a reasonable goal for people who have not lived with diabetes for many years or do not have complications that affect the test results. Studies have shown that glycohemoglobin values in the “better” ranges correlate with fewer diabetic complications later in life. 

  • American Diabetes Association goal is an A1c less than 7%.
  • The American College of Endocrinology goal is an A1c less than 6.5%.
  • For some people with diabetes an A1c goal of less than 6% is appropriate.

However, growing clinical evidence shows that relying on average blood sugar leaves out the frequency and severity of swings, which themselves are associated with complications independent of average. Some clinicians believe that very flat—but not necessarily very low—sugars might produce acceptable outcomes: A1c perhaps as high at 7.5% or even 8% in type 2 diabetes. Studies are underway to assess the relative importance of average sugar versus large sugar swings.

Continuous Glucose Monitoring

Available in the last few years, a continuous glucose monitoring system (CGM) measures and records glucose levels in the body’s interstitial fluid, which surrounds tissues and cells, throughout the day and night. Most often, CGM is used for up to seven days, recording up to 300 discrete data points.. Information from the sensor is downloaded continuously and analyzed when needed. Because the meter’s sensor is not very accurate, these devices must be calibrated with standard finger-prick meters. At a certain point, the sensor is removed and replaced.

The main advantage of continuous glucose monitoring is that it can help identify fluctuations and trends that would otherwise go unnoticed with standard HbA1c tests and intermittent finger-stick measurements. The device can be used continuously or intermittently. Some choose to wear the sensor to fix specific problems or just before a visit to their diabetes team.  Using CGM improves blood glucose control because it provides data than can help you minimize the time spent with high or low blood sugars.

There are some caveats and drawbacks that should be discussed with your doctor.

Monitoring Ketones

Ketones and ketoacids are alternative fuels made by the body by breaking down fats when glucose is in short supply to the cells. The fats travel through the blood to reach the liver, where they are processed into ketone units, which then circulate back into the bloodstream and are picked up by the muscle and other tissues to fuel metabolism. When there is not enough insulin, the fat cells keep releasing fat into the circulation, and the liver keeps making more and more ketones and ketoacids. The rising ketoacid levels make the blood pH too low (diabetic ketoacidosis), which is an emergency medical situation and requires immediate care.

Ketones also develop when there is inadequate glucose due either to a low glucose level or inadequate carbohydrate intake. This form of ketosis does not create a medical emergency.

Tracking ketone levels is clearly vital—fortunately, it’s a simple urine test. A blood test can also measure ketone levels. There are several circumstances that calls for ketone testing, including sick days or any time blood glucose levels have been very high for two tests back to back.

Keeping Records, Solving Problems

Good data is critical in evaluating how well you’re managing type 1 diabetes. Good data collection calls for good record-keeping. Writing the numbers down makes it easier to see your blood sugar patterns and know when you are on target or not. For most people, memory isn’t trustworthy when it comes to multiple blood sugar numbers, food content, and other factors operating at the same time as a blood sugar check.

In addition to blood sugar results, you should record your insulin dose, food and carbohydrate intake, and activity level. Logbooks designed for diabetes record keeping are widely available, and several smartphone apps now available can streamline the task. Your doctor may recommend a certain kind, and of course, the data you collect will be shared with your medical team to aid decision making. Keeping records as accurate as possible will help you all make the best choices.

Pump and CGM software can play a role in record keeping. Some devices that control both CGM sensors and pump can keep all your data, if you are willing to enter exercise and food by hand.

Managing your diabetes means maintaining the proper balance between insulin dose, food and activity every day. Put simply, if you are out of balance, your blood sugars will be too. However conscientious you are in working to keep blood sugars in a target range, sometimes you’ll miss.

There are many possible causes of excessively high or low blood sugars. Low sugars can result from “stacking” insulin (adding more insulin before the previous bolus of insulin has finished working), eating less carbohydrate or more fiber than anticipated, increased activity or exercise, or stress. Common causes of high blood sugars include “out-eating” the insulin dose, inadequate insulin dose, or a rise in stress hormones. To do the necessary problem solving, you’ll rely on blood glucose readings, carbohydrate counts, medication doses, and your logbook entries. To analyze the data:

  • Divide the day into zones: for example, morning, afternoon, evening, overnight.
  • Look for blood glucose patterns. When are you on target? When are you either too high or too low?
  • After you identify the problem, try to identify possible causes, rank them by which is most likely, then aim to fix the most likely cause.
  • Connect the dots. Do problems with high or low blood sugar crop up at the same time each day? After you eat? After you exercise? When you’re relaxed? After you take medication/insulin? When you’re stressed?

Then minimize the variables to narrow down the cause(s). In making corrections, follow these guidelines:

  • Make one change at a time
  • Verify that what you’re changing fixes the problem. If not, then reassess the possible causes. It could be the second reason on your list.
  • Talk to your diabetes team for help in analyzing your data.

Tight Control: What Is It, Who Is It For?

Tight control is a method of intensive diabetes self-management aimed at keeping blood glucose levels as close as possible to normal as you safely can—that is, without causing severe or frequent episodes of hypoglycemia.

For decades researchers debated whether aggressive blood glucose control could lower the risk of developing diabetic complications, including eye disease, kidney disease, and nerve disease. A few large clinical trials put the debate to rest: the closer you can get to nondiabetic blood sugars over time, the less likely you are to develop complications. So the ADA and other leading organizations have begun to define tight control in terms of numeric values and urged most people with diabetes to strive for these more stringent goals.

The best-known of these clinical studies is the Diabetes Control and Complications Trial (DCCT), from 1993. Here’s what it found in the tight-control group as compared with the standard-treatment group.

  • Diabetic eye disease started in only one-quarter as many people.
  • Kidney disease started in only half as many people.
  • Nerve disease started in only one-third as many people.
  • Far fewer people who already had early forms of these three complications got worse.

No single range of blood glucose levels works for everyone, though and these goals must be set  individually. Not everyone is a good candidate for tight control. The risk you run in shaving close to low blood sugar is more hypoglycemic episodes. People who strive for tight control must pay more attention to diet and exercise, measure your blood glucose levels more often, and recalibrate their dosage and scheduling of insulin.

Here’s a personal perspective from Scott King, founder of Islet Sheet Medical:

“I have been diabetic long enough to remember when tight control was controversial. Fortunately, my doctor was prescient about it. Not long after I was diagnosed, in 1977, Dr. Andrew Drexler told me,  ‘As you know I think tight control is a good idea. The clinical study [the DCCT] that is going to prove that tight control prevents vascular disease is about halfway done and is looking promising. So let’s stick with your tight control. I don’t want your kidneys to fail.

“My experience of managing diabetes in the thirty years since then argues that, with the technology now available to us, the goal for most people should be to simulate the control given by natural islets of Langerhans—in therapeutic language, tight control. As the tools get better (I love CGM, don’t know how I did without it!). the tightness of control possible evolves. And even the definition is changing, as we come to realize that some aspects of good control are not measured by A1c.”


  • Good management = trying to approximate the healthy metabolism of a person without the disease. It starts with frequent monitoring of blood glucose levels.
  • Experts debate different methods of evaluating blood-glucose levels and ideal target ranges. Whatever standards you and your medical team use, keeping good records of blood-glucose measurements is essential.
  • “Tight control”—intensive diabetes self-management aimed at keeping blood glucose levels as close as possible to normal as you safely can—has been shown to reduce future complications of type 1.