What is Hyperinsulinemia?

Hyperinsulinemia is characterized by abnormally high insulin levels in the blood and is a condition associated with type 2 diabetes, but alone it is not technically a form of diabetes. Hyperinsulinemia is also a factor in insulin resistance, obesity, and metabolic syndrome. It can be difficult to diagnose hyperinsulinemia, as symptoms are often unnoticeable. It's usually diagnosed through a blood test when checking for other conditions, such as diabetes.

Hyperinsulinemia Symptoms

An excess of insulin can result in low blood sugar being circulated throughout the body, and hypoglycemia (or the condition of having low blood sugar) may be an indicator to its presence. This is particularly noted in infants born to mothers who have uncontrolled diabetes.

Hyperinsulinemia is generally asymptomatic, meaning symptoms of the condition may not be noticeable. However, obesity may sometimes be a clue to underlying hyperinsulinemia.

In some circumstances, such as when a tumor (insulinoma) causes low blood sugar or hypoglycemia, symptoms may include:

• Increased cravings for sugar and carbohydrates
• Fatigue
• Difficulty losing weight
• Frequent hunger or extreme hunger

In infants and young children, hyperinsulinemia may present as:

• Fatigue or lethargy
• Difficulty feeding
• Extreme fussiness or irritability

Causes

Insulin is a hormone produced by the pancreas that has many functions. One of insulin's main functions is to transport glucose (sugar) from the bloodstream into the cells where it can be used for energy. In some people, insulin does not work properly because cell receptors have developed a resistance to insulin, which means that insulin is ineffective at removing glucose from the bloodstream. This condition is called insulin resistance.

Consequently, glucose builds up in the bloodstream. Because the body is unable to access the glucose for fuel, the cells become starved and you may feel excessively hungry or thirsty. The body attempts to lower blood sugar levels by releasing even more insulin into the bloodstream. As a result, the body ends up with both high blood sugar levels and high insulin levels. 

Some experts think that hyperinsulinemia is caused by insulin resistance, while others posit that insulin resistance causes hyperinsulinemia. Regardless of the underlying etiology, the two states are closely intertwined. When blood sugar increases, the pancreas' beta cells respond by producing and releasing more insulin into the bloodstream to try to keep blood glucose at a normal level. As cells become insulin resistant, the level of insulin keeps rising up.

The way insulin is metabolized in your body may depend on your race, gender, age, and environmental factors, as well as diet and activity level. All of these separate factors may be tied to your insulin sensitivity—more research is needed to fully understand all the causal factors.

Hyperinsulinemia may also occur as a side effect of Roux-en-Y gastric bypass surgery, which may be related to altered nutrient transit due to the newly created stomach pouch and bypassed gastrointestinal tract. However, this may be temporary. Researchers have found this effect may be reversible with the placement of a gastronomy tube in the original stomach.

In rare cases, hyperinsulinemia may be caused by a tumor of the beta cells of the pancreas (insulinoma) or by excessive growth of the beta cells, a condition called nesidioblastosis.

Complications

Several complications may arise as a result of hyperinsulinemia—making the issue seemingly more widespread than once assumed. Focusing only on blood glucose metrics may miss the fact that high levels of insulin can mask 'normal' markers of glucose tolerance and may be hiding a poor insulin response.

In fact, hyperinsulinemia is considered an early indicator of a larger metabolic dysfunction, and has been linked to the following complications:

• Cardiovascular disease
• Type 2 diabetes
• Alzheimer's Disease
• Hyperglycemia or high blood sugar from insulin resistance
• Some types of cancer, due to the stimulation of insulin-like growth factor 1 (IGF-1)

Pregnancy and Hyperinsulinemia

In pregnant women with uncontrolled blood sugar levels, the fetus is exposed to high levels of sugar. In response, the fetal pancreas undergoes changes to produce more insulin. After birth, the baby will continue to experience excess levels of insulin or hyperinsulinemia and will experience a sudden drop in blood sugar levels. The baby is treated with glucose after delivery and insulin levels usually return to normal within two days.

Diagnosis

Hyperinsulinemia may be diagnosed by testing your blood insulin and glucose levels. It may also be diagnosed by routine blood tests when undergoing testing for diabetes or other conditions, such as high cholesterol.

The primary test for assessing insulin levels is an "insulin in blood" test, which is a fasting test that involves taking a small sample of blood from a vein in your arm and assessing your insulin levels. Your healthcare provider will likely also request a fasting blood glucose test and possibly a hemoglobin A1c to get a handle on your glycemic control, as well.

Your insulin levels are considered normal if they're under 25 mIU/L during a fasting test. One hour after a glucose administration, they may increase anywhere from 18-276 mIU/L. If your insulin levels are consistently this high or even more elevated, even when fasting, you could be diagnosed with hyperinsulinemia.

Treatment

The ideal treatment for hyperinsulinemia will depend on first identifying the root cause, whether that may be obesity, insulin resistance, or something else, such as related to an insulinoma or nesidioblastosis, or the result of a gastric bypass.

Treatment options primarily include medication and lifestyle changes similar to those for type 2 diabetes.

Medication

The medications used to treat hyperinsulinemia are generally the same as those used to treat type 2 diabetes. However, medication should be secondary to diet and lifestyle changes.

Additionally, some diabetes medications actually increase insulin levels while working to lower blood sugar levels. One drug that successfully lowers both blood sugar and insulin levels and works to enhance insulin's action is metformin.

Beyond metformin, other medication classes approved as an adjunct to diet and exercise to improve glycemic control in people with diabetes include: sulfonylureas; thiazolidinediones; DPP-4 inhibitors; SGLT2 inhibitor; GLP-1 RA, or basal insulin.

Exercise

As exercise has been shown to improve insulin resistance, engaging in a physical activity regimen may be helpful as treatment for hyperinsulinemia. Exercise may also help reduce obesity. Just be sure to talk to your doctor before undertaking a new exercise program.

There are three types of exercise that may be useful in improving insulin sensitivity:

• Resistance exercise: This type of exercise incorporates weight lifting or exercises that utilize your own bodyweight to work one set of muscles at a time, usually with lots of repetitions and long rest periods in between sets. Resistance training may increase muscle mass, which can help with glucose absorption and reduce the reliance on insulin.
• Aerobic exercise: This type of exercise conditions the cardiovascular system and works multiple muscle groups at a time. Low- to mid-intensity aerobic workouts may include walking, jogging, swimming, biking, or dancing. Aerobic exercise or cardio may be similarly helpful in increasing glucose uptake and decreasing insulin.
• High intensity interval training (HIIT): This type of exercise incorporates short bursts of vigorous activity followed by periods of lower intensity to help with endurance and quick recovery. HIIT has been shown to improve insulin sensitivity, and some HIIT training sessions can be completed in just seven minutes—which is ideal if you don't have a lot of time to devote to working out.

Diet and Nutrition

Healthy eating, especially a diet that is lower in carbohydrates, may be especially helpful in improving insulin sensitivity, reducing blood glucose levels, as well as keeping weight in check. Three diets have been well-studied for their benefits on glycemic control and hyperinsulinemia:

• The Mediterranean Diet: Focuses on lean protein, low amounts of red meat, plenty of vegetables and fiber from whole grains, and plant-based fats, such as olive oil and olives.
• A Low-Fat Diet: Focuses on keeping fat low (around 20 to 35% of calories), carbs relatively high (around 45 to 65% of calories), and protein moderate (10 to 35% of calories).
• A Low-Carb Diet: Focuses on keeping carb counts very low (anywhere from 10 to 40% of total calories), while increasing fat intake but keeping protein moderate.

No matter which diet you choose or how you ultimately balance your macronutrient ratio (your ratio of carbs/protein/fat), aim to eat primarily whole, unrefined foods; including plenty of vegetables, fruit, lean proteins, whole grains and fiber-rich starches, while limiting processed foods and foods with added sugar or artificial sweeteners.

Additionally, a diet that's very high in protein may cause insulin to increase, so excess amounts of protein should be avoided, too.

Work with a nutritionist, your doctor, or a certified diabetes educator to create a diet plan that works with your lifestyle and needs.

A Word From Verywell

With the help of your care provider, hyperinsulinemia can be well-managed and controlled thanks to both medication and lifestyle changes, such as eating a balanced diet and incorporating more exercise. However, there has been an increase in recent research on the connection between hyperinsulinemia, type 2 diabetes, and obesity, which could progress further if the condition is left unchecked. Be sure to keep up with yearly blood tests through your physician and keep an eye on any new symptoms that arise.