Hyperglycemia is the clinical term used to describe unnaturally high blood glucose levels. Hypoglycemia, on the other hand, is when blood glucose levels get too low. The World Health Organization has defined hyperglycemia as above 125 mg/dl for fasting blood glucose, and above 200 mg/dl within two hours after eating.

Hyperglycemia is one of the principle symptoms of both type 1 and type 2 diabetes, and is also associated with prediabetes and diabetes risk factors such as insulin resistance and metabolic syndrome. Extreme levels of stress and hormonal imbalance in non-diabetic individuals can also potentially cause hyperglycemia.

Frequent levels of hyperglycemia in prediabetics will often lead to type 2 diabetes and increased risk of coronary heart disease(CHD) and cardiovascular disease(CVD).

Untreated hyperglycemia in both type 1 and type 2 diabetics will lead to numerous and potentially life-threatening diabetes complications, such as heart disease, stroke, neuropathy, nephropathy (kidney disease), periodontal disease, retinopathy, Alzheimer’s disease and dementia, amputations and skin infections.

Hyperglycemia in type 1 diabetics results because the beta-cells in the pancreas have stopped producing enough insulin to metabolize glucose in the bloodstream. In type 2 diabetics, hyperglycemia may occur because cells in the body have stopped responding to insulin properly, or the insulin producing cells in the pancreas have become exhausted and are not producing enough of the hormone. Sometimes a combination of the two may also occur.

Consuming processed foods, especially refined carbohydrates and sugary beverages, have the highest risk of causing hyperglycemic episodes. This is because these processed foods are digested extremely quickly, with the carbohydrates quickly being converted into glucose. This “fast” glucose then floods into the bloodstream. This can happen with other less processed high glycemic load foods and beverages as well, with fruit juice being a notable example.

The symptoms of hyperglycemia typically include increased thirst, frequent urination, blurred vision and fatigue. In severe cases, if left untreated a hyperglycemic episode can lead to shortness of breath, vomiting, ketoacidosis, and a “diabetic coma,” which can potentially result in death.

It is very important for diabetics and those diagnosed with prediabetic conditions such as metabolic syndrome, to live healthful and active lifestyles, eat balanced diets based on whole and fresh foods, and judiciously monitor blood glucose levels to ensure that hyperglycemia and hypoglycemia episodes are not taking place. For those with type 1 diabetes and advanced stages of type 2 diabetes, administration of insulin or other diabetes medications may be necessary to prevent hyperglycemia.

Resources and Further Reading

Diagnosis criteria for diabetes and hyperglycemia from the World Health Organization: 

A summary about  hyperglycemia: 

A good resource for understanding carbohydrates, blood sugar and an introduction to glycemic index and glycemic load: 


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