September 16, 2025, 2:53 pm | Read time: 4 minutes
The horse constantly stands by the water, appears tired, and loses weight—signs that many owners initially don’t associate with diabetes. However, in horses, a disrupted sugar metabolism can have serious consequences: PETBOOK explains the causes, symptoms, and treatment options.
In a healthy horse, the hormone insulin ensures that glucose from the blood enters the body cells and is used there as an energy source. However, if the horse has diabetes, this mechanism no longer functions properly. The body cells no longer respond adequately to the hormone. Although insulin is present, the cells can only absorb glucose insufficiently. The result: The blood sugar level remains permanently elevated, while the cells have too little energy available.
Causes of Diabetes in Horses
Unlike humans, horses almost always have insulin resistance—a lack of insulin is rare. Diabetes mellitus in horses usually develops as a secondary condition, such as from Cushing’s syndrome, but it can also occur independently. The disease often appears in combination with Equine Metabolic Syndrome (EMS). Typical signs of EMS include disturbances in sugar metabolism, laminitis, and fat deposits on the mane crest, hips, tail base, or belly.
Risk factors for developing diabetes include overfeeding, lack of exercise, and genetic predisposition. Breeds that are easy keepers, such as Shetland ponies, Haflingers, or Arabians, are particularly susceptible, while thoroughbreds are rarely affected. A diet rich in energy and protein can also promote obesity and thus increase the risk.1
Untreated diabetes in horses leads to a chronic inflammatory state that significantly impairs the horse’s health over time.
Recognizing Symptoms in Daily Life
It often begins gradually: The horse drinks unusually large amounts, appears lethargic, and loses weight despite normal food intake. The coat looks dull and brittle, and the shedding process takes unusually long. While other horses are already in their fresh summer coats, the affected animal still carries its winter coat.
The immune system also seems weakened: The animals fall ill more quickly, appear listless, and lose enthusiasm for movement. Despite normal or even increased food intake, some horses visibly lose weight. Often, signs of laminitis appear, which can be associated with Equine Metabolic Syndrome (EMS). Lameness and a heavy, irregular gait are common consequences.
How the Veterinarian Makes the Diagnosis
If you observe these symptoms in your horse, it’s time to take action. Typically, the veterinarian will take urine and blood samples. In a laboratory analysis, the samples are checked for glucose levels. Important: The samples should not be taken immediately after food intake, but rather before. Otherwise, the results may be skewed.
Clinics can also analyze and assess fat distribution and nutritional status. Additionally, the hooves should be X-rayed to rule out laminitis. At the same time, other conditions should be excluded, such as Cushing’s syndrome.2
Recognizing and Treating Laminitis in Horses
Horse Not Shedding Its Winter Coat? It Could Be Due to This Disease
Treatment of Diabetes in Horses
Treating diabetes in horses usually requires long-term therapy. A tailored, individual diet plays a central role. A needs-based feeding consultation is advisable. An optimized exercise program helps support regulation.
Accompanying illnesses should definitely be treated as well. In some cases, medications can also provide support. While direct insulin therapy is standard for dogs or cats, it is rarely used in horses.3
Prevention Can Be Helpful
Nutrition plays a central role in preventing and treating metabolic disorders in horses—especially supporting a healthy gut flora. It is crucial to limit the intake of starch- and sugar-rich feed. Ensure you provide suitable feed for diabetic horses and avoid constant access to highly sugary pastures.
The basis of feeding is high-quality roughage, primarily hay. Careful selection of suitable varieties is worthwhile. Besides the quality of the feed, feeding management is also crucial: Slowing down feed intake helps regulate consumption, and a hay net can be particularly helpful. Regular feeding times are essential, and long feeding breaks should be avoided.