Unstable or “brittle” diabetes is a term used to describe hard-to-control cases of diabetes in which glucose (blood sugar) levels swing unpredictably. At times the glucose tends to be too high (hyperglycemia), and other times it is too low (hypoglycemia).

Unstable diabetes usually refers to severe, uncontrolled forms of type 1 diabetes, but it can also describe poorly controlled cases of type 2 diabetes. It most often affects type 1 diabetes patients who are 15 to 30 years of age. However, the condition is also evident in elderly people with type 1 or type 2 diabetes.

Causes of unstable diabetes include many lifestyle factors that patients can change, including:

• Poor diet
• Lack of exercise
• Stress
• Problems with insulin administration
• Not taking medications as directed
• Not performing glucose monitoring as directed

Unstable diabetes can also occur when a person is unable to recognize problems with low glucose (hypoglycemia unawareness). Signs of unstable diabetes include periods of hypoglycemia or hyperglycemia, rapid changes in glucose or unpredictable morning glucose. These signs are sometimes severe enough to require hospitalization.

Unstable diabetes cannot be diagnosed with any single blood test. The condition, however, may be detected with tests that are used to evaluate how well a patient is managing diabetes over intervals of weeks or months.

Carefully adjusting insulin doses, frequently checking glucose and following a sick-day plan can help prevent diabetes from becoming unstable. Possible treatments include patient education, improved glucose meters, insulin pumps, new antidiabetic agents, a pancreas transplant or an islet cell transplant.