Diabetes

Symptoms

How does diabetes affect the body?

To properly process the carbohydrates in food, the body breaks them down into glucose (“blood sugar”) to use for energy. Then, the pancreas produces insulin to move the glucose from the bloodstream into cells.

In type 1 diabetes, the body does not properly make insulin. This type is thought to be caused by a combination of genetics and environmental factors and is generally first diagnosed among youths. However, there are also adult-onset cases of type 1 diabetes.

As for type 2 diabetes, the body does not respond properly to the insulin that it makes. This is called insulin resistance. Early in the disease, the body makes more insulin to compensate. But, over time, the body cannot keep up, and insulin deficiency develops as type 2 diabetes progresses.

With gestational diabetes, a pregnant woman develops diabetes during her pregnancy even though she has never had it before.

What are the long term complications of diabetes?

There are a multitude of long-term complications of diabetes that are caused by elevated blood glucose levels over time. These include heart disease, stroke, high blood pressure, kidney nephropathy (disease) possibly leading to kidney failure requiring dialysis, poor circulation and foot ulcers potentially leading to limb amputations, peripheral neuropathy (nerve damage causing pain), autonomic neuropathy (causing erectile dysfunction, gastroparesis, etc), other neuropathy (such as Charcot neuropathic arthropathy), vision loss (due to diabetic retinopathy, glaucoma, or cataracts), skin infections or other problems. Diabetics have nearly double the risk of heart attack or stroke compared to people without diabetes.

Are those complications only the result of blood sugar or are there other factors involved?

There are certainly genetic and environmental risk factors for cardiovascular disease, high cholesterol, kidney disease, and vision impairment or loss that are distinct from the presence of diabetes.

However, diabetics are more likely to develop these diseases or conditions than people without diabetes. For all complications of diabetes, improved blood glucose control will decrease the risk of developing them, as will controlling blood pressure and quitting smoking.

Causes

Which type of diabetes is most prevalent?

About 90% of people with diabetes have type 2. Unfortunately, type 2 diabetes used to occur primarily in adults. However, with dietary changes, decreased physical activity, and increasing rates of childhood obesity, we are seeing more cases of type 2 diabetes among children.

What are the most important causes of type 2 diabetes? How much do genetics matter?

Scientific consensus is that environmental/lifestyle factors combined with genetic risk are the primary causes. According to the WHO (World Health Organization), approximately 80% of new diabetes cases have been attributed to the rise in obesity in the US.

Prior studies have estimated that a person is about three times more likely to develop type 2 diabetes if they have a first degree relative (parent, sibling) with diabetes. That said, the degree to which this is genetic rather than caused by similar eating and exercise habits among family members is not known.

There are also ethnic and geographic trends, with diabetes being more common among Native Americans, Alaska Natives, African Americans, and Hispanics.

Prevention

How preventable is diabetes?

It is possible to delay or prevent diabetes by exercising, eating well, losing weight, and quitting smoking. Multiple studies of pre-diabetic patients, including the Da Qing study, the Finnish Diabetes Prevention study, and the Diabetes Prevention Program study, have shown that intensive lifestyle interventions can reduce the incidence of developing diabetes by 43-58%.

What is “prediabetes”?

Prediabetes occurs when a person’s blood glucose levels are above normal, but not yet at a level that is defined as type 2 diabetes. Prediabetes is defined as a fasting blood glucose level of 100-125 mg/dL. A person with prediabetes is at increased risk of developing full-blown type 2 diabetes.

For people with prediabetes, is it possible to still prevent diabetes?

Yes, by managing your weight, changing your diet, increasing your amount of exercise, and quitting smoking. The Diabetes Prevention Program (DPP) showed that intensive lifestyle changes aimed at modest weight loss decrease the risk of developing type 2 diabetes by 58% at three years and by 34-49% at 10 years.

For people who have diabetes, when’s the best time to make changes? Is it ever “too late?”

The sooner healthy lifestyle changes are made the better. But, even if you’ve had diabetes for years, making adjustments to your diet, exercise habits, and losing weight can improve your diabetic control, blood pressure, and cholesterol levels.

It is expected that lifestyle changes can also decrease your risk of cardiovascular and other diabetic complications (though no long-term studies have been completed to look into this, there are trials currently underway to examine this).

There is limited evidence in various journals (JAMA, BMJ) to suggest that intensive lifestyle modification and weight loss can cause partial, or less commonly, complete remission of diabetes.

How and why have the rates and patterns of diabetes changed over the last 20 years?

Per the NIH Genetics Home ReferenceHow preventable is diabetes? , the incidence of diabetes has more than quadrupled in the past 35 years due to increased sedentary lifestyle, poor diet, obesity, and other risk factors. Particularly concerning is the trend towards younger adults and children developing type 2 diabetes.

It is possible to delay or prevent diabetes by exercising, eating well, losing weight, and quitting smoking. Multiple studies of pre-diabetic patients, including the Da Qing study, the Finnish Diabetes Prevention study, and the Diabetes Prevention Program study, have shown that intensive lifestyle interventions can reduce the incidence of developing diabetes by 43-58%.

What is “prediabetes”?

Prediabetes occurs when a person’s blood glucose levels are above normal, but not yet at a level that is defined as type 2 diabetes. Prediabetes is defined as a fasting blood glucose level of 100-125 mg/dL. A person with prediabetes is at increased risk of developing full-blown type 2 diabetes.

For people with prediabetes, is it possible to still prevent diabetes?

Yes, by managing your weight, changing your diet, increasing your amount of exercise, and quitting smoking. The Diabetes Prevention Program (DPP) showed that intensive lifestyle changes aimed at modest weight loss decrease the risk of developing type 2 diabetes by 58% at three years and by 34-49% at 10 years.

For people who have diabetes, when’s the best time to make changes? Is it ever “too late?”

The sooner healthy lifestyle changes are made the better. But, even if you’ve had diabetes for years, making adjustments to your diet, exercise habits, and losing weight can improve your diabetic control, blood pressure, and cholesterol levels.

It is expected that lifestyle changes can also decrease your risk of cardiovascular and other diabetic complications (though no long-term studies have been completed to look into this, there are trials currently underway to examine this).

There is limited evidence in various journals (JAMA, BMJ) to suggest that intensive lifestyle modification and weight loss can cause partial, or less commonly, complete remission of diabetes.

How and why have the rates and patterns of diabetes changed over the last 20 years?

Per the NIH Genetics Home Reference, the incidence of diabetes has more than quadrupled in the past 35 years due to increased sedentary lifestyle, poor diet, obesity, and other risk factors. Particularly concerning is the trend towards younger adults and children developing type 2 diabetes.

Treatment

What medications are used for diabetes?

The most common oral medication is Metformin, which is one of the first-line agents to treat most patients with type 2 diabetes.

Sulfonylureas (glipizide, glimepiride, glyburide, etc) were previously considered second-line agents. However, a recent study published in the BMJ showed an increased risk of cardiovascular complications and hypoglycemia (low blood glucose) in patients who were treated with sulfonylureas alone.

Other classes of oral medications include thiazolidinedione, meglitinides (repaglinide, nateglinide), sodium-glucose co-transporter 2 (SGLT2) inhibitors (dapagliflozin, canagliflozin, etc), dipeptidyl peptidase-4 (DPP-4) inhibitors (sitagliptin, saxagliptin, linagliptin, etc), alpha-glucosidase inhibitors (acarbose, miglitol, etc). There are also injectable agents, which include glucagon-like peptide-1 (GLP-1) agonists (exenatide, liraglutide, lixisenatide, dulaglutide, semaglutide, etc) and Pramlintide.

If a patient fails oral therapy or if their blood glucose or A1C are above a certain level, insulin may be added. There are short-acting insulins that are given with meals, long-acting insulins that provide a basal insulin coverage for the body, and intermediate-acting insulins that are a blend of the two. The goal of insulin treatment is to replace or supplement the body’s natural insulin production to control blood glucose.

How effective are diabetes medications? If people are on non-insulin medications, how much can they do if other factors are/are not changed?

“Well-controlled” diabetes is defined by a hemoglobin A1C of less than 7% (this is an indirect measurement of the average blood glucose over the past two-to-three months).

Non-insulin diabetes medications all have an impact on blood glucose, though to varying degrees and with varying risks of side effects. The oral medications can be used as monotherapy or in combination with other medications. Some patients can use a single medication with good control.

If control is suboptimal, a combination of medications may be used. When used in combination, the effects of medications are additive, though not linearly so. The most effective medications for lowering blood glucose—which include Metformin and Sulfonylureas—decrease A1C by 1-2%. Other classes decrease A1C by ~0.5-1% depending on the medication. To give a comparison, a single daily injection of long-acting insulin can decrease A1C by 1.5-3.5%.

There is certainly a limit to how much improvement in glycemic control medications can provide. So, although they will help improve diabetic control, the maximal benefit will be achieved if patients commit to lifestyle changes as well

Diet

What’s the best diet for diabetes prevention/treatment?

A “Western diet” that is high in processed and red meat, fried foods, dairy products, refined grains, sweet drinks, and desserts is associated with higher rates of diabetes, cardiovascular disease, and other ailments. This is what not to do.

By contrast, the best diet for diabetes prevention and/or treatment is a balanced, healthy diet that incorporates five servings of vegetables and fruits per day, is high in dietary fiber, and is low in sugars, saturated and trans fats, and processed food.

Diabetics should also pay attention to how many calories they are eating, and try to avoid foods with high glycemic index. Foods with a low glycemic index have a slower rate of absorption into the bloodstream, so they cause less of a blood sugar spike. A great list of the glycemic indexes of different foods can be found at the Harvard Health Publishing site.

Are all carbohydrates created equal when it comes to blood sugar and diabetes? Why or why not?

Not all carbohydrates are created equal, so it is important to choose the healthy ones. The best sources of carbohydrates are from vegetables, fruits, whole grains, legumes/beans, and dairy products. The worst are from processed foods and sugars.

Furthermore, new evidence is emerging showing that non-nutritive sweeteners, which are the sweeteners for “diet” products, have a multitude of negative health impacts, so they should be avoided as well.

For diabetics with a sweet-tooth, it's always better to select a natural, unprocessed fruit-based dessert rather than a dessert that is processed.

What about fruit and vegetables? Should people with diabetes stay away from fruit?

Fruits and vegetables are an extremely important part of a healthy lifestyle for everyone, including diabetic patients.

A large study in the British Medical Journal in 2014 showed that a higher intake of fruit and green leafy vegetables was associated with a significantly reduced risk of developing type 2 diabetes. Eating fruits and vegetables also lowers the risk of developing high blood pressure, heart disease, strokes, obesity, and some cancers.

It is a common misconception that diabetics should avoid fruit. Fruit provides important antioxidants, fiber, vitamins, and minerals. Also, less insulin is required to metabolize fruits than is required for the equivalent amount of refined sugar. Diabetics should choose fruit wisely and count it as part of their overall carbohydrate intake. A great strategy is to replace a treat of candy, muffin, cake, or ice cream with a piece of fruit.

Vegetables are extremely important to health and, as mentioned above, should make up ½ of any plate of food that you eat. Diabetics should avoid starchy vegetables; a great list of non-starchy vegetables can be found on the ADA site.

Are diet products and sugar substitutes good alternatives?

New evidence suggests that diet products and artificial sweeteners are not good alternatives despite previous recommendations. Multiple studies have shown increased rates of cardiovascular disease, stroke, dementia, and all-cause mortality with increased consumption of artificially sweetened foods and beverages.

There is one sugar substitute that may not fall into this category: Stevia is a non-calorie sweetener that is derived from the Stevia rebuadina plant. Stevia has been shown to lower blood glucose levels in diabetics, and some studies have even suggested that it may improve glucose tolerance. Although stevia at this time seems like a good alternative to sugar and artificial sweeteners, more research is still being done to determine its effects.

Lifestyle Factors

What’s the best exercise for diabetes prevention and treatment?

The American Diabetes Association recommends 30 minutes of moderate-to-vigorous aerobic exercise at least five times per week, plus strength training (resistance training) at least two times per week. If your schedule does not allow 30-minute blocks of exercise time, you can break them into 10-15 minute blocks for the same benefit.

Some diabetic patients are not physically able to do the recommended moderate to vigorous physical activity. But evidence shows that even walking, yoga, or Tai Chi can improve blood glucose control in diabetics.

Do sleep and stress matter?

There is data suggesting that sleep of poor quality or short duration is linked disordered glucose metabolism, which can lead to increased likelihood of developing diabetes and, among existing diabetics, worse glucose control. However, more studies are needed to investigate this link.

In regard to stress, the link between stress and glucose is still being examined. There are some studies showing that stressful situations alter blood glucose levels, though the full impact of this on diabetics in real-life situations is less clear.

In 2017, one study followed over 12,000 women for 12 years and found that high levels of stress increased the risk of developing type 2 diabetes. There is also good evidence that high stress negatively impacts diabetes control because stress limits a person’s ability to follow their meal plan, check their blood sugar, and take medications/insulin appropriately.

Does smoking cigarettes have any impact on diabetes?

Smoking increases your risk of developing type 2 diabetes. According to the CDC, smokers are 30-40% more likely to develop type 2 diabetes than nonsmokers. Multiple studies have shown this link, including a review article published in JAMA that showed that the risk of diabetes was highest for heavy smokers and lowest for former smokers.

The mechanism for this effect is multifactorial and still being explored. In people with diabetes, smoking makes glucose levels and/or insulin dosing harder to control. Current evidence demonstrates a similar pattern of smoking worsening insulin resistance in diabetics.

Smoking also increases the likelihood of complications in diabetic patients, including heart and kidney disease, retinopathy, peripheral neuropathy (nerve pain in arms and legs), and poor blood flow to the legs and feet that can cause infections, ulcers, and amputations. Quitting smoking should be a priority for everyone and there are many resources to help in the difficult path to quitting.

Are any herbs or supplements effective?

There are a range of herbs and supplements that are being evaluated for their potential to improve diabetic control. But more research is needed, since many of these have only been used in animal models or in small-scale human trials.

Some of the natural products that have shown potential for use in diabetic and pre-diabetic patients include American ginseng, Coccinia indica, aloe vera, cinnamon, fenugreek (Trigonella foenum-graecum), curcumin, and the leaves of Olea europaea. However, it's always a good idea to talk with your doctor prior to starting any of these supplements.

What do you think are the biggest unanswered questions and/or areas for new discovery in diabetes?

There are some very interesting studies looking at stress hormones and inflammatory markers in the body, and examining how higher levels of these hormones/markers might be linked to diabetes and a number of other diseases.

Useful Links

A good go-to resource (American Diabetes Association)

Basic information for type 2 diabetes (CDC).

Information on the National Diabetes Prevention Program (CDC)

Diabetes Diet Tips (Diabetes.org)

Healthy diet plate composition (USDA)