Insulin and Insulin Sensitivity
Insulin is an important hormone that helps transport nutrients – especially glucose (sugar) – to cells to be utilized or stored. Insulin sensitivity refers to how well your body utilizes that glucose.
In someone with poor insulin sensitivity, the body either produces more insulin than is necessary or the insulin secreted is not as effective as it should be. This can be due to overproduction of insulin by the pancreas and/or desensitization of the target tissues (muscle, liver, etc.). Either way, what you’re left with is excess glucose in the blood, and chronically elevated blood glucose levels are a significant factor in the onset of type 2 diabetes.
Insulin resistance, or poor insulin sensitivity, is largely the result of poor lifestyle habits. While genetics can set the stage for issues with blood glucose regulation, poor dietary habits, excess body fat, and physical inactivity are what propel the problem into full blown diabetes.
The major causes of poor insulin sensitivity include the following:
• Genetics – A family history of type 2 diabetes is associated with an increased risk for insulin resistance and type 2 diabetes
• Excess body fat – Diabetes risk increases significantly for men with a waist circumference 40 inches or more and women with a waist circumference 35 inches or more
• Physical inactivity – A lack of regular physical activity predisposes to type 2 diabetes as well as myriad other diseases including hypertension and heart disease
• A diet low in omega-3 fats – especially DHA and EPA from fatty fish and/or fish oil
• A diet high in refined carbohydrates – sugar, high fructose corn syrup, white flour, etc.
• Nutrient deficiencies (especially magnesium and vitamin D)
• Chronic sleep deprivation
• Gestational diabetes
• Medications – especially glucocorticoids, thiazides, beta blockers, atypical antipsychotics, and statins
When muscle, liver, and even fat cells no longer respond to insulin and the pancreas can no longer produce enough insulin to clear the blood of glucose, blood sugar becomes chronically elevated and type 2 diabetes is diagnosed.
The following chart lists diagnostic criteria for type 2 diabetes:
|Diagnosis||Glucose tolerance test* (mg/dl)||Fasting glucose test** (mg/dl)||HbA1c*** (%)|
|Type 2 diabetes||≥200||≥126||≥6.5|
*A glucose tolerance test is when a sugar drink is given and a blood sample is taken afterward – typically two hours later – to determine how much glucose has been cleared from the blood.
**A fasting glucose test is when a blood sample is taken after a 12 hour fast to determine how much glucose is in the blood.
***HbA1c, or glycosylated hemoglobin, is a longer-term measure of the amount of glucose in the blood based on how much is bound to hemoglobin.
Excessive amounts of sugar in the blood may not sound particularly harmful, but the complications it can cause are serious. Long-term effects of elevated blood sugar include heart disease, stroke, peripheral neuropathy (including pain and weakness), loss of eyesight, kidney failure, and limb amputations. These issues can largely be avoided, however, by engaging in proactive methods of improving insulin sensitivity.
Six Ways to Improve Insulin Sensitivity
1. Move more
Walk, run, bike, hike, lift weights, do P90X or Crossfit or even dust off your Tae Bo® Cardio Kickboxing DVDs – whatever it takes to get you to move. Regular physical activity is the single best thing you can do for your overall health; it is also one of the most effective ways to improve insulin sensitivity and prevent and fight diabetes.
Both cardiovascular and resistance exercise can improve insulin sensitivity by:
- Reducing body fat
- Increasing lean muscle mass
- Reducing elevated blood sugar levels
- Improving cellular glucose uptake
If you’re new to working out or you’ve had a long layoff, start with 30 minutes of low to moderate intensity activity a few days per week and work up in difficulty and duration. Be sure to include cardiovascular and resistance exercise (weight training) for maximum benefit.
2. Lose excess body fat
This goes hand-in-hand with number one. In many cases, insulin resistance and type 2 diabetes can be reversed through exercise and weight loss and without the need for any prescription drugs or therapies. A simple body fat test [link to Bod Pod] can reveal exactly how much excess fat you need to lose, and tracking body circumferences can help track changes in body fat distribution.
3. Go low carb
If you’re overweight your insulin sensitivity is already poor, so continuing to consume copious amounts of refined carbohydrates is going to lead to more fat gain and a greater risk of developing type 2 diabetes. As a general rule, the more overweight you are the fewer carbohydrates you should consume. Another good general rule is to eat the bulk of your carbohydrates in the morning or after a workout, the two times of day when insulin sensitivity is highest. Carbohydrate sources should include starchy vegetables, fruit, rice, quinoa, and high-fiber, whole grains.
4. Eat less fructose and trans fatty acids
Fructose and trans fats have both been shown to promote insulin resistance. That means you should avoid sugar (which is 50% fructose), high fructose corn syrup, fruit juice, margarine, shortening, fried foods, and partially hydrogenated oils. You’re probably asking, “What about fruit?” since fruit does contain fructose. The amount of fructose in fruit is small (< 10 grams for the average serving) and fruit contains vitamins, minerals, phytonutrients, and fiber that offset the negative effects on insulin sensitivity.
5. Eat more omega-3s
Shifting the balance of fatty acids towards the anti-inflammatory omega-3s (n-3) – especially EPA and DHA found in fish oil [link to Omega-3 Performance] – will improve cholesterol ratios, decrease elevated triglycerides, and reduce the risk of insulin resistance. Increasing your n-3 fatty acid intake is as simple as eating more fish (especially sardines, herring, mackerel, and salmon), eating grass fed meat, and/or supplementing with fish oil.
6. Use beneficial foods and supplements
There are numerous foods, herbs, and nutrients that can positively influence insulin sensitivity. Some of the more effective ones are listed below:
- Apple cider vinegar
- Green tea extract
- Panax ginseng
As you can see, a few simple lifestyle and dietary changes, and some beneficial foods and supplements, can improve your insulin sensitivity and help prevent type 2 diabetes.
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