Diabetes is the condition of high blood sugar levels for a long period. It causes symptoms such as frequent urination, increased hunger and thirst, etc. Various serious complications such as cardiovascular disease, chronic kidney disease, and stroke can occur due to high blood sugar levels. One of the most complex conditions that occurs due to diabetes is hyperglycemia. It is a condition where an excessive amount of glucose circulates in the blood plasma. It is majorly caused by diabetes mellitus and acute stress such as stroke. The growth hormone, glucagon, cortisol and catecholamines may also cause hyperglycemia. Certain medications such as corticosteroids, octreotide, statins and niacin, increase the risk of hyperglycemia. It can also occur due to insulin resistance which obstructs the process of the conversion of glucose into glycogen and makes it impossible to be removed from the blood. The general symptoms of hyperglycemia include blurred vision, fatigue, restlessness, weight loss, dry and itchy skin, polyuria and polydipsia. Its treatment requires the reduction of the underlying cause like diabetes. Acute hyperglycemia is treated by giving insulin while severe hyperglycemia is treated with oral hypoglycemic therapy. This book provides comprehensive insights into hyperglycemia. The book presents researches and studies performed by experts across the globe. Those in search of information to further their knowledge will be greatly assisted by this book.