Diabetes comes in a few different medical configurations.
Type 1 Diabetes (insulin-dependent diabetes) was once called juvenile diabetes because it appears mostly in childhood or early teens. Insulin, the hormone responsible for storing glucose (blood sugar) and fats, fails completely and has to be replaced by injected insulin. Without insulin, glucose and fat and derivative products called ketones build up to dangerous levels in the blood. An autoimmune reaction that destroys the insulin-producing cells in the pancreas is thought to be responsible for type 1 diabetes.
Type 2 Diabetes (non-insulin dependent diabetes), is mostly a disease of lifestyle. Obesity and lack of physical activity are the main drivers of type 2 diabetes or insulin-independent diabetes. For most type 2s, some insulin is active, but the mechanism of storage does not work as well as it should. This is called glucose intolerance and insulin resistance. Glucose and fats again rise in the blood and cause problems. Unless treated, serious health outcomes such as blindness, kidney failure, heart disease, neuropathy and other complications can occur. More or less complete insulin failure or ineffectiveness (secondary failure) can occur in type 2 diabetics, in which case insulin injection is required.
Gestational Diabetes occurs during pregnancy and although potentially serious, usually abates after the birth. It may indicate susceptibility to type 2 diabetes later in life.
LADA or Latent Autoimmune Diabetes of Adulthood is diabetes that does not appear to be lifestyle related but has similar features to type 1 diabetes including failure of insulin production.
Pre-Diabetes is a condition in which blood glucose (sugar) is high, but not high enough for a diagnosis of type 2 diabetes. It may be reversed with weight loss and exercise.
Diabetes Insipidus is a rare form and not really related to types 1 and 2. It is usually a consequence of failure of a pituitary hormone called antidiuretic hormone. Symptoms are excessive thirst and urination. Specific treatments are available for this form of diabetes.
Lifestyle, Diet and Exercise for Type 1 Diabetes
I’ve described the different types of diabetes because the two main types — type 1 and type 2 — can be different in nature and different lifestyle approaches may be required.
In type 1 diabetes and LADA in the end stage, you have no insulin and you need to inject insulin. Type 1s learn from an early age how to manage their condition and to make sure they don’t have an insulin reaction that causes hypoglycemia (low blood glucose or ‘hypo’), or hyperglycemia (high blood sugar), both of which can cause serious adverse events including fainting and unconsciousness — and death if not treated. Type 1s always carry some form of glucose in candy or lollies or sweet drinks to address hypos. Injectable insulin also needs to be close by.
While physical activity is important for type 1s, they do have to ensure their insulin dose is adjusted accordingly because exercise may increase blood sugar (glucose) use, disposal and storage and the insulin dose may have to be adjusted to avoid hypos (low blood sugar).
For exercise instructors, it’s important to ensure the type 1 person (or type 2 on insulin) has received advice from their doctor or diabetes educator prior to any additional or more intense physical activity they are about to take on. Physical activity in type 1 diabetes is important for all the reasons that exercise is generally beneficial — heart disease protection, weight management, cancer prevention and possibly improvements in glucose disposal and HbA1c, a measure of blood glucose over time. In the past, high-intensity exercise has been regarded as potentially hazardous for type 1 diabetics, but this is no longer valid if the precautions mentioned above are observed. Some of the best athletes in the world are type 1 diabetics, including footballers, swimmers, skiers and basketballers. The exercise program described below for type 2 diabetics is suitable for type 1s.
Type 1s must learn about adjusting their eating and exercise habits to manage blood glucose and insulin. Other than that, no special dietary habits are required other than following a healthy, high-fibre dietary pattern and managing weight. Very low-carb diets are not necessary although some restriction of carbohydrates may work for some people struggling with general blood glucose control. See more about low-carb diets below. Carbohydrate counting and exchanges may be used to stabilise blood sugar.
Lifestyle, Diet and Exercise for Type 2 Diabetes
The first thing to make very clear is that for people with pre-diabetes or a diagnosis of type 2 diabetes, weight loss and increased physical activity is the number one priority after blood glucose is stabilised. Everything else is fiddling around the edges. Fixing these two lifestyle factors has been shown in trial after trial to help reverse pre-diabetes and to improve glucose control in type 2 diabetics as well as reduce HbA1C, the glycated hemoglobin that does damage to arteries and blood vessels, large and small.
Diabetics are mostly not in good physical shape. Before starting an exercise program, a doctor’s approval is a good idea, if not mandatory. Special considerations may be required for type 2s with certain medical conditions. These may need to be addressed before an exercise program is commenced. If on insulin and glucose-lowering medications, adjustment of the doses may be required with the introduction of an exercise program. Doctors and diabetes specialist advisors should be consulted.
With approval, a program within the general parameters of the following is suitable. I understand that this commitment won’t suit everyone. Even so, a structured program of general movement and activity, walking for example, on most days of the week for 30 to 45 minutes is a good basis for more advanced exercise involvement.
Day 1. Aerobic exercise. Walk or jog on a treadmill or outdoors for 30 minutes at moderate intensity. Moderate intensity means in the range 50% to 70% of your maximum heart rate or at a pace at which you can still talk easily enough or recite a poem for example. Swimming and cycling are fine for aerobic conditioning, but you don’t get the advantage of bone building that you do with impact exercise. Standard aerobics, step and pump group aerobics classes are excellent.
Day 2. Weight training. Use this Basic Strength and Muscle program as a guide. You can do this at a gym or you can do most of the exercises at home with a home gym or even a set of dumbbells. The individual exercises are not that critical, but you need to work all of the major muscle groups including the upper and lower legs, arms, shoulders, back, chest, abdominals and buttocks. The reason for this is that the more muscle you exercise and build, the more depots for glucose disposal and storage you create.
Do 8 to 10 exercises including 3 sets of 8 to 12 repetitions in each set. Adjust the load so that you can get through a complete set and so that the final repetition, say number 10, is getting a little harder to do. At the end of the third set of any exercise you should be working somewhat hard but not busting your gut. Rest for two to five minutes before the next exercise.
When starting out, it is important not to overdo things. Do fewer sets or repetitions and use less weight if you need to, but do all exercises and progress to higher volumes and intensity. However, strength and muscle training needs to stress the muscles appropriately. Lifting light dumbbells for 20 repetitions, although not useless, is not what’s required here. Take it easy, but not too easy!
Day 3. Aerobic training as for day 1.
Day 4. Aerobic training as for day 1.
Day 5. Weight training as for day 2.
Day 6. Aerobic training as for day 1.
Day 7. Rest.
With increasing fitness, you can gradually increase the intensity and volume of your exercise program. Employing a qualified trainer with experience in training diabetics is recommended but not strictly necessary if you take it gradually and consult often with your doctor on wellness issues. This program is suitable for type 1 diabetics as well, notwithstanding advice regarding insulin adjustment.
Nutrition and Diet
The current dietary recommendations and guidelines for type 2 diabetes and pre-diabetes from the American Diabetes Association is available. The general composition of diets recommended for type 2 diabetes is not too different from healthy eating recommendations overall. They should be low in saturated fat and trans fat, high in fibre and low in glycemic index (GI). A diet constructed in this way is like to provide good glycemic (glucose) control, heart healthy eating and meet the recommended dietary intakes. Regular exercise will enhance the results. Carbohydrate counting and exchanges may be used to stabilise blood sugar if required.
Are low-carbohydrate diets useful?
Low-carb enthusiasts are keen to recommend low carb and even ketogenic diets for diabetes, both types 1 and 2. For the most part, I don’t agree that this is useful, although moderately low carbohydrate diets, say >40% carbohydrate might be beneficial for some people in some circumstances.
However, it’s not just about total carbohydrates or glycemic load. In at least two randomised controlled trials, (Wolever) and (Davis), HbA1C (glycated hemoglobin) was not lowered by low-carbohydrate diets after one year compared to high-carbohydrate diets.
In addition, in a low-GI vegan diet for treatment of type 2 diabetes (Barnard), beta cell function (insulin production) was superior with the low-GI vegan diet compared to a low-carb diet after 12 months. This is what the authors said:
“These results suggest that, in patients with type 2 diabetes on diet alone, a Low-GI diet for 1 year increases disposition index, an index of beta cell function, compared with a Low-CHO diet.”
It’s important to note that vegan diets are usually in excess of 70% carbohydrate. The lesson again is that it’s not the quantity, but the quality of carbohydrate that is most important. In this study, the carbohydrate was low-glycemic index and high fibre — whole grains, beans, pulses, fruits, vegetables. I’m not suggesting diabetics need to become vegans, but it is worth noting that glycemic control was improved on a very-high carbohydrate diet.
Low-carb diets also tend to result in a failure to meet recommended dietary intakes (RDI), the lower the diet is in carbohydrates. This may be avoided with very careful food selection, but as a public health recommendation, low-carb is going to fail most people in this respect, and you would need to have substantial nutrition knowledge to be sure all nutrients are covered. You can see a real analysis of a low-carb dietary regimen in this study by Jenny Shaw. Low-carb diets can be low in fibre, folate, calcium, magnesium and some fat-soluble vitamins.
In addition, low-carb diets do not offer any weight loss advantages after 12 months compared to high-carbohydrate diets. This has been shown in sufficient randomised trials for the issue to be settled.
Further, low-carb dieting has to mean high-protein and high-fat dieting. With many type 2 diabetics having chronic kidney disease, and being overweight, high-protein diets are likely to be a risky recommendation for any health professional advising such people — unless their personal liability insurance is in good shape!
One more thing about low-carb diets. Undiagnosed type 2 diabetics with extremely poor glucose control may be on the verge of ketoacidosis, which is a condition of metabolic acidosis when insulin production has just about ceased, blood glucose is high, and ketone bodies are produced in the body in excess. This is a dangerous condition and can be fatal. A low-carb, ketogenic diet could possibly aggravate such a condition by accelerating ketosis and thus ketoacidosis. Several case reports have already described the possibility of this occurrence (Shah, Chalasani).
Finally, diet and exercise choices are important over the long term. A high-fibre, low-GI, diet is likely to be the best choice, as reflected in the recommendations of many countries. Carbohydrate percentages are a moot point, but not a precise one, and moderately low-carb diets (>40%) may help some people with glucose control problems. Even so, the best options to replace carbohydrate in such instances are likely to be vegetable proteins and oils, or perhaps dairy protein — with no increases in red or processed meat consumption.
In conclusion, the best advice for which there is an ample evidence base for lifestyle modification, for type 2 diabetics and pre-diabetics (and type 1s for that matter), is to attain normal weight if possible, eat according to healthy eating guidelines with emphasis on high-fibre/low glycemic index foods, and to exercise most days of the week.