Blood Sugar Spikes 18 To 24 Hours After Exercise

I’m putting this out to/for my fellow type 1 diabetics out there.

It is well-documented that exercise in excess of 80% of threshold (think VO2 max) raises blood sugar rather than lowering it. If you go for a light jog, your blood sugar will go down. If you push hard and go for a super-fast run, you’ll probably end up raising your blood sugar. If you didn’t know this, then now you know. How do you use this information: if you plan on doing a very strenuous workout, do not take extra carbohydrate before exercising, and do not reduce your basal rate or long-acting dose. Test after exercising and correct as necessary.

But here’s something I cannot find any information on: When I engage in a very long bout of exercise – for example, a 10-mile long run – my blood sugar certainly comes down, but I have noticed a tendency to experience a rather large blood sugar spike 18-24 hours afterward.

I didn’t even notice this tendency until this morning, when I was reviewing my blood sugar log. Over the weekend, I had had what I classified as a “very mysterious high.” I remembered that this had happened a couple of weeks back, so I scrolled up and was amazed by how similar the readings were. I had had a long run on Saturday at about the same time of day; my before-breakfast readings were within 5 mg/dL of each other, and in both cases by 11 AM, my blood sugar had shot up beyond all explanation. In both cases, this was followed by near-identical lunches. Finally, in both instances, in the late afternoon I experienced hypoglycemic sensations, tested, and found I was in the 80s (mg/dL). Precisely the same experience, weeks apart.

Then I checked deeper into my log history and found a few more recent examples. That is, I logged blood sugar readings that followed the same pattern. It has been too long for me to remember the details of those older examples.

Please, please, PLEASE if for some reason you are a diabetic who sees this blog post, please leave me a comment and let me know whether you’ve noticed a similar phenomenon.

Fitness Experiments #2.2

So two rather significant workouts in one day lead to multiple mild blood sugar lows today. If you're diabetic like me, you should remember to back off on the long-acting insulin when you make significant increases to your daily training regimen.

I'm no doctor, so make sure you consult with yours. What I can tell you about is my own personal experience, which is this: Mealtime insulin seems to behave more or less the same way. What's changed is the fact that I feel like I have too much long-acting insulin on board. If you end up in the same boat I'm in today, then watch yourself very carefully.

For example, I woke up on time and ready to work out this morning, but promptly went hypoglycemic (mildly). Going for a run this morning would have been pretty stupid, so I skipped it, ate a predictable breakfast, and went about my day as usual.

This afternoon, I plan on doing last week's back/bicep workout (see Fitness Experiments #2), only in reverse, similar to what I did yesterday. But the fact of the matter is that I've trained pretty hard the last few days and I'm not going to push myself ultra licitum just for the thrill of it. If I feel a little unwell, I'll half my workout and get some food.

I do intend to workout twice tomorrow, but I will reduce my Lantus dose accordingly.

Be safe out there.

Diabetes And Exercise: Part IV

Recently, I have been exploring the some personal hypotheses related to human growth hormone (HGH), cortisol, and insulin and glucose levels in the blood stream. What began as a bit of a crackpot theory quickly grew into a relatively deep dive into some aspects of the endocrine system that are not directly involved in the insulin-glucagon-food-sugar cycle that so preoccupies us diabetics. I am still not fully comfortable discussing the information from any standpoint of expertise, and it should always be remembered that I am not any sort of an endocrinologist, not even an amateur one. Nevertheless, I do feel that I have sufficient knowledge of some of these concepts to merit a new installment of my Diabetes and Exercise series.

Anabolism And Catabolism
Metabolism consists of two separate processes that have fancy names, but which are fully intuitive. Anabolism is that part of metabolism that produces growth and generation. Catabolism is that part of metabolism that results in the breaking down of larger things.

A simplistic view of the process would cause a conceptual error. We would like to believe that anything that builds is good, while anything that deconstructs is bad. This is obviously not the case: fuel must be burned in order to produce energy, timber must be cut in order to build a house, and so on. In all cases, building something new involves breaking something else down to some extent or another. So long as we are not dealing with annihilation, we intuitively understand this concept.

So it is with the human metabolism: Catabolism breaks down larger molecules so that energy can be released into the body, anabolism combines energy, hormones, and proteins to produce muscle and tissue growth.

Recall from my "Hunting for Clues" post that HGH, which is primarily responsible for muscle growth, lipolysis, protein synthesis, etc., is produced as a response to strenuous exercise and/or hypoglycemia. Insulin levels therefore also impact the extent to which HGH production occurs.

The way this at least appears to me to work is that blood sugar levels have a tendency to fall when we fast (of course) and when we engage in activities that make use of the sugar in the bloodstream. Once the insulin/glucose ratio tilts to a certain point, HGH production kicks-in. The most immediate reason for this is to stimulate gluconeogenesis in the liver. That is, to keep us alive, HGH sends a signal to the liver to start cranking out the glucose. In a healthy body, this would continue up to the point where more reasonable blood-insulin and -glucose levels are established, at which time catabolic hormones (mostly glucocorticoids, I believe) would be released to send a signal to halt or slow gluconeogenesis and/or metabolize blood sugar.

It is a two-step process, and neither step is more important than the other. It is akin to taking a step with your right leg, followed by a step with your left leg, and thus, walking.

Diabetic Conditions (I Think)
Diabetic bodies being what they are, we are always warding-off conditions of hyperglycemia. Left without insulin injections, our blood glucose would rise and we would ultimately die because of it. This suggests (again, I must reiterate that I am hypothesizing based on my limited understanding of the situation) that diabetics with under-controlled blood sugar levels will also experience lower HGH production (since we will rarely be in hypoglycemic conditions, or even conditions of high blood-insulin levels regardless of blood glucose levels).

Combine this knowledge with the fact that exercise produces cortisol, a glucocorticoid. This means that a diabetic who exercises regularly will experience increased cortisol levels (as a direct stress response to the exercise itself) and increased hyperglycemia as a result of both being a diabetic in general and the fact that exercise also stimulates gluconeogenesis as the natural result of exercise-induced increased respiration.

What we are left with is a picture of a diabetic body under the conditions of strenuous exercise: heightened levels of blood glucose and glucocorticoids combined with inhibited levels of human growth hormone. The body is catabolizing, but not anabolizing. That is, the diabetic body breaks down, but does not build up. If you are a diabetic who exercises regularly, you have probably experienced the feeling that you are wearing yourself down: your muscles burn and feel fatigue for days on end, you're tired all the time, and so on.

The quirk here is that, as we all know, exercise also reduces blood sugar levels and can result in hypoglycemia if we're not careful. Our balance is therefore thrown out-of-whack. We get the worst of all worlds: increased blood sugar and cortisol, but no corresponding regulatory influx of HGH. Whatever hypoglycemia we experience is a result of our injected insulin. Because the body isn't producing that insulin itself [hypothesis alert], it appears that the normal anabolic signals fail to trigger the right way.

Making Use Of This Knowledge
Over the past few weeks, I have been experimenting with my new-found knowledge. There are a few simple things we diabetics can do improve our anabolic profile. Doing so will reduce our blood sugar, reduce the amount of daily insulin required, and hopefully help us all better-regulate our bodies.

First, it has been shown that eating a small amount of protein after every workout results in a slight inhibition of the production of cortisol. I have spent almost a year drinking very-low-carbohydrate (~3mg or so) protein shakes after every workout. The low levels of carbohydrate prevent me from going hypoglycemic before I can get to a safe a place with necessary snacks, while the protein serves to reduce the body's post-workout stress response. I feel much better having had a protein shake after a workout than I do otherwise. It does at least appear to work.

Second, it is extremely helpful to use one's workouts to foster the production of HGH. As I have noted, strenuous exercise stimulates HGH production. The operable word is strenuous. If you are like me, then you have grown accustomed to working out a particular way. For example, I spent whole years of my life going for a daily 10-mile run. Before I was diabetic, this worked okay (although it wasn't ideal). When I became diabetic, however, the daily 10-mile run created conditions in my body in which I was producing copious amounts of cortisol due to the stress of the workout, but the workout was never so stressful as to result in much HGH production. My blood sugar would gradually increase, until I would eventually have to take significant time off running.

In contrast, these days I have taken to dedicating about three days per week to a very strenuous strength-and-plyometrics workout that completely exhausts me, after which I will often go for a modest run on top of that. Such workouts are so strenuous that my body cannot help but crank out the HGH. Yet, because I only do this three times per week, my body never gets so worn-down from exercise that I hurt my muscles, bones, or ligaments. The remainder of the days of the week are spent doing a more traditional cardio workout, like a daily run. This seems to produce the right balance of HGH versus cortisol.

Third, it is very important that an exercising diabetic reaches a state of deep sleep on a regular basis, because it is during this deep sleep that the majority of a person's HGH is produced. Every diabetic who has ever had to stay up at night has feel the awful burning sensation of lacking sleep. That burning sensation is cortisol pumping through the human body: losing sleep is stressful. But the foregone HGH production serves up a double-whammy for the exercising diabetic, further worsening our blood sugar profile.

Conclusion
Considering the above discussion, there are a few important take-aways to be had:

• Diabetics risk diminished anabolism
• There are proven activities that promote anabolism in the body
• Hyperglycemia and cortisol production worsen a diabetic's blood sugar profile, but this is a condition that can be alleviated by engaging in activities that promote anabolism
• Dedicate three days per week to highly strenuous exercise, such as plyometrics
• Get plenty of sleep

To put it succinctly, if you're not gasping for breath, then you're not engaging in strenuous activity. You should be gasping for breath for a good thirty minutes solid. Doing so will promote HGH production and improve your blood glucose control.

It should be noted that much of what I have just written applies equally to diabetics and non-diabetics. For diabetics, it is uniquely important, but all of the above principles apply to people who simply wish to enjoy the anti-aging, immunity-boosting effects of natural HGH production.

Diabetes and Exercise Part III: After the Workout

Oops, I lied.

In my last article on Diabetes and Exercise, I promised that this article, Part III, would contain some tips on insulin dosing in light of special considerations for diabetics. However, when I sat down to write about those special considerations, I realized that I had left out an important aspect of exercise physiology: what happens after you exercise?

Understanding this question is vital to understanding how the diabetic's body reacts to exercise. The more intense the exercise, the more disruptive this reaction can be. So today, I'd like to provide some (very) basic information about the post-exercise phase of physiology. Just as in Part II, I'm going to keep this as simplified as possible, so that we can focus on the important information and not get caught up in a description of cellular respiration and biochemistry.

After The Workout: Anaerobic Exercise
Recall that in Part II, we learned that anaerobic energy is "ready-to-use" energy stored within the cells, waiting for the moment you move a muscle. It requires no insulin for immediate use, it simply fuels cell work and expires.

Think carefully about what this might imply about the body's next course of action. The stored energy that was once contained in the cells is now gone. The body will naturally act to replenish this energy. This act of replenishment does, in fact require insulin (and other hormones).

When you digest a meal, insulin helps carry glucose into the cells so that it can be converted into this stored energy. When you exercise, this stored energy is depleted and your body becomes "hungry" again. Whenever your body is hungry, it "feeds its cells" with whatever glucose is on-hand.

Therefore, immediately following a big burst of anaerobic exercise, the body starts drawing on its various sources of glucose (either the blood stream, fat deposits, as-yet undigested food, a post-workout Gatorade, whatever) and acts quickly to put that glucose back inside the body's cells.


It happens rapidly. Your body needs that energy immediately, not merely for the sake of exercise, but for the sake of getting around. What I mean is, let's assume you sprint as fast as you can for 200 meters. If you have given it a good effort, the muscles in your legs have expended so much of their stored energy that if that energy isn't replaced, you won't be able to walk. Indeed, track and field spectators have seen  many a 200-meter athlete collapse at the finish line, unable to continue to walk, much less run.

This is due to the fact that the body doesn't distinguish between "anaerobic energy used for sprinting" and "anaerobic energy used for walking." It's all the same stuff, and once it's gone, it's gone.

Now, here's what you need to know as a diabetic: When you engage in anaerobic exercise, your body will immediately act to replenish the energy you've used up. If the body does this too quickly or if you have used up too much of your stored energy, this will induce hypoglycemia.

After the Workout: Aerobic Exercise
When we engage in aerobic exercise, things follow a different path.

Recall that we learned in Part II that during cardiovascular exercise, we use up a little anaerobic energy to get started, and then the body phases-in aerobically generated energy to keep you going throughout your workout. This is what causes the heavy breathing, the elevated heartrate, and so forth. Your body is rapidly taking in oxygen to mix with sugar and insulin, and delivering it to your cells.

Once the workout is over, our bodies continue to have an elevated heartrate, we continue to breathe heavily, and our respiratory system continues to deliver aerobic energy into our cells. The process doesn't immediately end, it takes a little time to wind down, gradually.

Not only that, but aerobic respiration itself isn't a perfectly efficient process. You may have heard that your body "doesn't start to burn fat until twenty minutes into your workout." Twenty minutes is a ballpark figure, and in reality, the process is gradual rather than binary. But the bottom line is more or less true: It takes time for the body to be able to use the energy produced during aerobic respiration; it also takes time for the process to taper off.

This, too, functions as much logically as it does physiologically. What you might expect to occur within the body really does occur: Namely, our blood sugar remains elevated for some time after the workout, thanks to the gradual and inefficient nature of aerobic respiration. Eventually, though, it does taper off, and the energy must be replaced. The body once again gets "hungry" for more energy, and starts to transport any and all sugar from available sources into the cells so that it can be stored for future use.

Exactly how long this aerobic cycle lasts depends not only on your own unique body, but also on how fit you are, how hard you pushed yourself, and for how long you were exercising aerobically. It will not occur exactly the same way twice. In some cases, it will persist for twelve hours. Some endocrinologists have suggested to me that periods of longer than twenty-four hours are not uncommon.

Regardless, what's important for the diabetic to understand is this: Aerobic exercise will initially raise your blood sugar, and that rise in blood glucose will persist for quite some time after exercise. Eventually, however, the elevated blood sugar will subside as your body acts to replenish its stored energy - and this may induce hypoglycemia.

Some Closing Remarks/Discussion
I suppose the most vitally important thing to remember in all of this is that both anaerobic and aerobic exercise can induce hypoglycemia in a diabetic, for reasons I will (hopefully) elucidate in my next article. Therefore, always remain vigilant. Monitor yourself very carefully during and after exercise to ensure you are safe. It takes some experimentation to find out what your limits are and when you hit them.

I have to reiterate that because at every point in time, it is a diabetic's first priority to avoid life-threatening hypoglycemia. It is not the keystone of exercising as a diabetic, but it never goes away. We diabetics must simply and at all times think about hypoglycemia and how to avoid it. It is a fact of life for us.

So, the best recommendation I can give here is to always carry a little sugar with you when exercising, and always have a snack after the workout. No more than 15g of carbohydrates, and if I were you, I would not take it in the form of sugar. 

Having looked after that top priority, we can then dive into the details and nuances of the remaining information. We can then start analyzing how our bodies will react to various workouts to which we might subject it.

For example, an interval workout at the track will result in a particular "blood sugar reaction" afterward; a fifteen-mile long run will result in a different, no less unique reaction. And not only is the workout important, the sequence is, too. Lifting weights and then doing some cardio will do something different to your body than doing cardio and then lifting some weights.

In subsequent articles in this series, I will explore some of the considerations involved in the types of workouts you might choose, and the types of reactions we can expect from them.

Diabetes and Exercise Part II: Exercise "Physiology"

Last week, I introduced this series of posts on diabetes and exercise by taking a look at the things you'll need as a diabetic aiming to start an exercise regimen.

To take the next step, you should be aware of some of the things that occur in the human body - diabetic or otherwise - when we exercise. While having some knowledge of the science behind fitness is highly beneficial for everyone, it is particularly valuable for us diabetics. The reason for this pertains to something I mentioned last week:

When it comes to exercise, you will have to start assessing the impact of different kinds of exercise, and different levels of exertion, on your body and blood sugar. As we will see in subsequent posts in this series, the impact of exercise may be immediate, or it may be delayed up to twenty-four hours in the future! As you start out, these impacts seem erratic and unpredictable. So the better-informed you are and the better-aware you are of short- and long-run trends, the better you will be able to control your blood sugar with exercise.

Let's try to take some of the guess-work out of it, shall we?

A Two-Penny Science Lesson
I've read a few physiology books, had all the important biology classes, and applied the principles to my own life through personal experimentation. What I've learned, is that the average person doesn't need to take a deep dive into biochemistry in order to understand what's going on when they exercise. So, I'm about to give you the simplest lesson in exercise physiology you've ever had...

If we ignore the various chemical transformations that occur during human respiration, we can focus on what's really important to the task at hand. To wit, all human energy is made up of the following components:

1. Sugar
2. Water
3. Air
4. (Insulin)

When you begin to exercise, your body draws on the energy that has been previously converted from sugar, water, and air, and then stored in your cells. The fuel used to create this energy comes from the food you've been eating lately, the water you've been drinking, and whatever oxygen has been culled from your casual breathing. (Insulin is the hormone mechanism that is responsible for delivering the sugar from the bloodstream into the cells.)

This is obviously a limited energy source that can only get you so far. In order to exercise for a prolonged period of time, the body must reach a point where it is converting fuel (sugar, water, and air [and insulin]) into energy on-the-fly and utilizing it to the extent that it can be generated.

This second type of energy is built from the water that happens to be in your body right now, the air that you're breathing right now, and whatever sugar can be had on a moment's notice. Now, everyone has a given quantity of sugar in their bloodstream at all times, so this is the body's "first stop" for aerobic fuel. The next stop is whatever sugar exists in as ready a state as the body can find, starting with the easiest-to-access and progressing steadily toward the most remote sources of sugar. (Insulin is utilized at all stages, because it is required to deliver the sugar into the cells.)

The "stored energy" in this case is anaerobic energy. We use it for short bursts, i.e. lifting weights, sprinting, kicking at the end of the race, and so on. The "directly converted energy" in this case is aerobic energy. The important takeaway here is this: anaerobic energy utilizes energy that is stored readily inside your cells; aerobic energy must be generated and transported into the cells from outside sources first.

Discussion
It is tempting to say that we use aerobic energy for aerobic, i.e. cardiovascular, exercise and anaerobic energy for everything else, but this is not exactly how it works. Technically speaking, everything the body does involves a blend of the two. There is a sequence that is as much logical as it is physical.

The body can't start doing something unless it employs anaerobic energy. Were this not the case, you would have to engage in heavy breathing for several minutes before you did anything simple, like type an email or lift a fork to your mouth to eat. Anaerobic energy, then, is a ready-source of energy that is employed whenever your muscles first act to do something.

Note carefully: A technical feature of anaerobic energy is that it does not require insulin for immediate use. While your body had to utilize insulin in order to store the energy, simply using it once stored requires no insulin at all.

If you have experience lifting weights, you know that the body can often reach a point where further action becomes impossible. You can no longer lift your arms, your legs stop moving, your muscles burn. Even if it doesn't hurt, there is no point to further physical expenditure - it will not occur. This physical barrier is your body running out of anaerobic energy; there is no more left to be had.

If you are engaged in a lighter, more repetitive movement (like running, for example), then your body has an opportunity to generate some aerobic energy before it completely runs out of anaerobic energy. Your heart starts beating rapidly and you start to breath heavily. After some time, the cardiovascular process has generated enough energy to feed the cells during the exericse. Aerobic energy, then, is the energy generated by an individual's ability to create movement from fuel on-the-go.

Note again: As implied from the above, aerobic energy requires a ready source of insulin. Without it, aerobic respiration cannot produce any energy at all. That is why you as a diabetic may have felt your body start to burn and reach a point of exhaustion in a matter of minutes.

Of course, aerobic respiration is not a perfectly efficient process, so eventually this energy source also declines and the body experiences exhaustion. Extending the length of time required to fully exhaust the body is what endurance training is all about. As you engage in endurance training, your body learns to become more efficient at processing aerobic energy. It does this by growing tailor-made muscle tissue that is particularly adept at this, and also by increasing the amount of oxygen that can be stored in the blood at any given moment. (For water, you pretty much just have to stay hydrated.)

In contrast, strength training does not improve the body's efficiency for utilizing anaerobic energy because the process is already highly efficient. Instead, the body grows additional muscle cells so that there is more anaerobic energy "on hand" for the next time you sprint or lift something heavy. In essence, the body builds more storage for immediate energy, but continues consuming it at about the same rate.

Conclusion
Now that you have a general idea of how the body is making use of its energy, you are ready to apply these principles to your own diabetic body. Because diabetics are less-able to engage in the energy conversion process (either from lack of insulin or the incidence of insulin resistence), some extra consideration is required to understand how we can best exercise, what we can expect as we start to undertake a new exercise regimen, etc.

So, in my next article in this series, I will discuss some special considerations for diabetics, including some words on insulin dosing, planning, etc.

Diabetes and Exercise Part I: Preparation

Introduction
Today I thought I would kick off a new series of blog posts in which I intend to share information about Diabetes and Exercise that I have collected over the past few years.

When initially diagnosed with diabetes, patients hear a chorus of voices instructing them to exercise regularly, stay healthy, and of course watch what they eat. This advice sounds identical to Type 1 patients and Type 2 patients, despite the two types of diabetes mellitus being radically different conditions. As a result, much of the diabetes advice out there tends to paper-over the important details that differentiate the two. It results in some good soundbites, but also a great deal of confusion on the patients' part.

At least, that was my experience. As a result, much of what I know about diabetes and exercise so far is the result of my own reading and self-experimentation. That may not sound like a ringing endorsement of what I am about to write, but unlike the authors of the soundbites in your diabetes pamphlets, I embrace the fact that all bodies are different. Therefore, the most important thing to take away from this series is that each patient needs to exercise, observe, and carefully evaluate ever new exercise activity's impact on his/her body and adjust accordingly.

In short, no one set of "rules" will fit your own specific case. You need to become a "tinkerer" when it comes to figuring out what your body can do. The aim of this series is to share my own experiences with "tinkering," in hopes of helping you figure out how to do it yourself.

What You Need To Get Started
Any discussion of diabetes and exercise logically begins with a brief lesson on exercise physiology. However, I thought it best to delay that lesson for the time being to focus on more practical matters. If you're going to take on a new exercise regimen as a diabetic, you will have certain unique requirements that other people who exercise do not have to worry about.

Know Your Numbers
First of all, throughout this series - and elsewhere throughout my blog - I will be referring to various values for blood sugar readings. We in the United States measure those values in milligrams per deciliter, while those of you in other countries measure it in millimoles per liter.

A simple Google Calculator search will provide you the conversion directly, but if you'd like a bookmark to go back-and-forth between conversions, here is a handy online calculator for you.


Emergency Sugar
The first thing you need is an emergency source of sugar to protect you in the event that you experience hypoglycemia.

Let's start at the elementary level and answer the question that the absolute-beginners might have at this point: I thought lowering my blood sugar was the point - what's the problem with hypoglycemia? It's true that we aim to decrease our blood sugar with exercise, but keep in mind that lowering it below 72 mg/dL (4.0 mmol/L) sends the body into shock and creates a risk of potentially fatal seizure.

More to the point, as your blood sugar falls below the normal range, you will experience impaired mobility and cognition, and will begin to be less-able to help yourself. If this happens, you need sugar fast, and that's where your emergency stash comes in.

The recommended approach for treating hypoglycemia is to ingest 15mg of fast-acting sugar, wait 15 minutes, then test to ensure your blood sugar is back in the normal range. Repeat as many times as it takes to get you back to normal.

What works? Lots of people use candy (such as LifeSavers), and some people chew dextrose (pure sugar) tablets. I was a competitive athlete years before ever having to think about diabetes, so I prefer using sport gels, such as my personal favorite, Hammer Gel:

It should go without saying that if you experience exercise-induced hypoglycemia, you should stop exercising for the rest of the day.

Insulin
I haven't needed this one myself, yet. We'll get to the issue of exercise-induced hyperglycemia in a subsequent post, but for now, you should simply be aware that some people need to carry insulin with them in the event that their blood sugar increases dramatically to dangerously high levels. If this happens, a corrective bolus of rapid-acting insulin will be required to return your body into a safe state of being.

You can help avoid this by never exercising when your blood sugar is above 288 mg/dL (16.0 mmol/L), or when there are ketones present in the urine stream. If you are new to all of this, then you will get a feel for this stuff as you go.

Blood Glucose Meter
If you are worried about hypo- or hyperglycemia, you should take a blood glucose monitor with you when you exercise and test if you feel unwell. Fair disclosure: I skip this step myself, because I have done enough historical testing before and after workouts at various times of day and at various points before and after meals to understand what I am capable of.

But that is a level of experimentation I necessarily had to engage in. If you are less experienced, it is worth getting some blood glucose data behind you so that you can exercise in an educated manner.

A Spreadsheet
I have a spreadsheet that tracks my blood glucose readings. Various vendors make software that facilitates this, but I find a simple Excel spreadsheet or Google spreadsheet document does the trick just fine.

When you test your blood sugar, no matter how regularly, you often see a different picture when you're "in the moment," taking each reading one-by-one than you do when you collect all your readings by date, time of day, and relevant activity (before meal, after meal, before exercise, etc.) and go searching for trends.

When it comes to exercise, you will have to start assessing the impact of different kinds of exercise, and different levels of exertion, on your body and blood sugar. As we will see in subsequent posts in this series, the impact of exercise may be immediate, or it may be delayed up to twenty-four hours in the future! As you start out, these impacts seem erratic and unpredictable. So the better-informed you are and the better-aware you are of short- and long-run trends, the better you will be able to control your blood sugar with exercise.

Additional Tips For Starting Out
A few more things to keep in mind as you start out exercising with diabetes:

1. For now, don't make radical changes to your diet. We diabetics have to tightly control what we eat to ensure that we stay healthy and keep control of our blood sugar. That means you will have to resist a lot of fitness-industry pressure to radically alter your diet in accordance with current fads. You may eventually choose to alter your diet according to what works best for you. But starting a new exercise regimen is a big change for your body. If you make two big changes at the same time, you are changing two variables, and it will be difficult to determine which of the two had a more relevant impact on your blood sugar. Change one, then change the other; don't change both at the same time.
2. It is always a good idea to let someone else know where you're going. If you go for a walk, a run, a swim, a bike ride, whatever, take the time to let someone know what route you're taking and how long you think you'll be. You will probably not get into trouble out there, but if you do, you'll be glad that you let someone else know where to go looking for you.
3. If you work out with a friend, let them know how to help you in an emergency. I wear a Medic-Alert dogtag and I always take time to let people know that if they see me pass out, they need to put sugar under my tongue and call an ambulance. Nine words that require less than two seconds to state could save your life some day: "Put sugar under my tongue and call an ambulance." Simple as that.
4. If you have an insulin pump, turn it off.

In my next article in this series, I'll cover the physiological effects of exercise and what that implies about your blood sugar. Until then, give exercise a try and see what you can learn on your own!