Yes, diarrhea can lead to high blood sugar levels, particularly for individuals managing diabetes. The link is not direct, but results from the body’s complex physiological reaction to the stress of illness and subsequent fluid loss. When the body faces a gastrointestinal illness, it initiates responses designed to fight the infection, which can disrupt glucose regulation.
How Diarrhea Elevates Blood Glucose Levels
Illness activates the body’s defense mechanisms, often leading to hyperglycemia. The physical stress of feeling unwell triggers the release of counter-regulatory hormones, such as cortisol and adrenaline, into the bloodstream. These stress hormones signal the liver to ramp up its production of glucose through gluconeogenesis, releasing stored sugar into circulation. This surge of new glucose, combined with the hormones’ ability to reduce insulin sensitivity, results in blood sugar levels climbing high.
Severe fluid loss caused by diarrhea is a second significant factor. This rapid depletion of water and electrolytes leads to hemoconcentration, where the blood becomes thicker and more concentrated. While the absolute amount of glucose in the body may not have changed, the ratio of glucose to plasma volume increases, causing a much higher reading on a blood glucose monitor. Dehydration also impairs kidney function, reducing the organ’s ability to efficiently filter and excrete excess glucose through the urine.
The Impact on Oral Diabetes Medication
Diarrhea can directly interfere with the effectiveness of diabetes treatment. Oral diabetes medications rely on a specific absorption time within the gastrointestinal tract to enter the bloodstream and exert their glucose-lowering effect. Diarrhea speeds up the transit time of contents through the gut.
This rapid movement can cause the medication to be excreted before it has fully dissolved or been absorbed into the body. The result is a lower-than-intended dose, leading to a loss of blood sugar control and subsequent hyperglycemia. While injectable insulin is not subject to the same absorption issue, the overall stress and dehydration from the illness still necessitate careful monitoring and potential dosage adjustment for all people with diabetes.
Managing Blood Sugar During Gastrointestinal Illness
Managing blood sugar during a gastrointestinal illness requires a proactive approach often referred to as “sick day rules.” Constant fluid intake is paramount to combat the dehydration and blood concentration caused by diarrhea. Sip 6 to 8 ounces of fluids every hour while awake, ideally alternating between plain water and sugar-free electrolyte solutions to replace lost minerals.
Frequent glucose monitoring is necessary, requiring checks at least every two to four hours, even overnight, to track any rapid changes. If blood sugar levels are consistently high (over 240 mg/dL or 13.3 mmol/L), it becomes necessary to test for ketones, which signal that the body is breaking down fat for energy.
Individuals should never stop taking their long-acting or basal insulin, even if they cannot eat, because the stress hormones still elevate blood sugar. For oral medications, or for adjustments to fast-acting insulin doses, immediate consultation with a healthcare provider is necessary. A doctor will provide guidance on whether to temporarily stop certain oral medications, particularly those that can be risky during dehydration, and how to adjust insulin to cover the elevated glucose levels.
It is important to know when to seek emergency medical care. Symptoms requiring immediate attention include:
- Persistent vomiting.
- Diarrhea lasting more than 24 hours.
- Inability to keep any fluids down.
- Signs of severe dehydration, such as excessive thirst.
- Symptoms of Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS), including confusion, rapid breathing, or fruity-smelling breath.