Vomiting in a person with diabetes signals a significant disturbance in metabolic balance and should never be overlooked. Vomiting accelerates the risk of severe dehydration, which rapidly worsens high blood sugar levels. The inability to keep down food or fluids disrupts the precise timing of medication and insulin, initiating a dangerous cycle of metabolic instability. Understanding the cause is paramount, as it may signal a life-threatening acute crisis or a long-term complication.
Acute Metabolic Crisis: Diabetic Ketoacidosis (DKA)
Diabetic Ketoacidosis (DKA) is an acute, life-threatening complication occurring most frequently in Type 1 diabetes, but possible in Type 2 diabetes under stress. DKA is triggered by a severe lack of insulin, preventing cells from using glucose for energy. The body switches to burning fat for fuel, producing acidic byproducts called ketones.
The excessive buildup of these ketones makes the blood dangerously acidic, a state known as ketoacidosis. This highly acidic environment directly irritates the digestive system, causing the characteristic severe nausea and projectile vomiting associated with DKA. Other symptoms include excessive thirst, frequent urination, and deep, labored breathing known as Kussmaul respiration, as the body attempts to expel carbon dioxide to correct the acid imbalance.
A distinct symptom of DKA is a fruity odor on the breath, caused by the exhalation of acetone, one of the ketone bodies. Severe abdominal pain, which can mimic other medical emergencies, is also a common complaint that resolves once the underlying acidosis is treated. If not treated quickly with intravenous fluids and insulin, DKA can lead to confusion, decreased consciousness, and coma, requiring immediate medical attention.
Chronic Digestive Complication: Gastroparesis
A separate cause of persistent vomiting is Gastroparesis, a chronic condition related to long-term nerve damage from consistently high blood glucose levels, a form of diabetic autonomic neuropathy. High glucose levels damage the vagus nerve, which is responsible for controlling the muscles of the stomach. This nerve damage causes delayed gastric emptying, meaning the stomach muscles move too slowly to push food into the small intestine.
Because food remains in the stomach for an abnormally long time, symptoms often include early satiety, bloating, and recurring vomiting. A distinguishing feature is that vomiting often occurs many hours after a meal, and the vomited material may contain undigested food. The unpredictable timing of food absorption caused by gastroparesis can also lead to wide, difficult-to-manage swings in blood sugar, increasing the risk of both hypoglycemia and DKA.
Intercurrent Illness and Medication Triggers
Vomiting can also be caused by acute illnesses not directly related to a diabetic crisis, such as a common stomach virus or gastroenteritis. When the body fights any infection or illness, it releases stress hormones like cortisol and adrenaline. These hormones oppose the action of insulin, causing blood sugar levels to rise and making diabetes management more difficult.
Certain medications used to manage diabetes commonly list nausea and vomiting as known side effects. Metformin, a widely prescribed first-line medication, frequently causes gastrointestinal upset, especially when a person first starts taking it or if it is taken without food. Injectable drugs like GLP-1 agonists (e.g., exenatide, liraglutide) also commonly cause initial nausea and vomiting, though these symptoms often lessen over time as the body adjusts.
Immediate Action and Monitoring Steps
When vomiting occurs, following “Sick Day Rules” is necessary to prevent the situation from escalating into a medical emergency. The first step is to check blood glucose levels every three to four hours, even if this means waking up during the night. If the blood glucose level is elevated (typically above 240 mg/dL or 13.3 mmol/L), checking for ketones in the blood or urine is the next immediate action.
The presence of ketones indicates that the body is breaking down fat for energy, and moderate to high levels signal the need for urgent intervention. A blood ketone level greater than 1.5 mmol/L or a high level on a urine strip requires an immediate call to a healthcare professional. A level over 3.0 mmol/L is a trigger for going to the emergency room immediately. Even if not eating, never stop taking basal or long-acting insulin, as stopping it completely will almost certainly lead to DKA.
If vomiting prevents food ingestion, the goal shifts to maintaining hydration and consuming small amounts of carbohydrates to prevent hypoglycemia. Aim to sip 6 to 8 ounces of fluid every hour while awake to combat dehydration. Fluids should alternate between sugar-free options like water or broth and carbohydrate-containing liquids such as juice or regular soda, especially if blood glucose levels are not highly elevated.
Certain diabetes medications, specifically Metformin and SGLT2 inhibitors, may need to be temporarily stopped during periods of severe vomiting or dehydration, but this should be done only after consulting a healthcare provider. Immediate emergency care is required if a person cannot keep down fluids for four hours, if blood glucose levels remain high despite following the sick day plan, or if signs of confusion or rapid breathing develop. Having a pre-established sick day plan with a healthcare team is the best preparation for managing these acute situations.