True diabetes is rare to arguably non-existent in rabbits. Good news for the vast majority of buns! It is so uncommon that rabbit-savvy vets with years of experience may never have had to diagnose and treat a case ... bad news for the unlucky patient.
Diabetes mellitus occurs due to a dysfunction of the pancreas. When enough insulin isn't secreted to control glucose levels, the amount of glucose in the blood rises. Most rabbits with diabetes or diabetes-like symptoms are overweight. Therefore, the issue can usually be resolved with a corrected diet.
Diagnosing diabetes in rabbits
Symptoms of diabetes in rabbits may be vague and can come on suddenly or gradually over time. Your rabbit may drink and pee more. She may eat more than usual but still lose weight. She may just seem more tired than usual or generally unwell.
Because the symptoms of diabetes can vary, it's important to rule out other possible causes, such as an endocrine disorder like Cushing's Disease or pancreatitis. Your veterinarian will probably run blood tests and do a urinalysis to check for glucose in the urine. Meryl Schimek, University of Wisconsin - Madison School of Veterinary Medicine 2018 DVM Candidate, recommends an additional blood test to measure fructosamine. "This differs from a spot glucose check in that it demonstrates the blood sugar changes over the last three weeks instead of one snapshot in time." Blood glucose can spike dramatically in stressed rabbits (a.k.a. most rabbits that find themselves at the vet).
Treating a diabetic rabbit
Prevention and treatment of diabetes in rabbits goes hand in hand: maintaining a healthy diet and healthy weight. An obese rabbit showing symptoms of diabetes can control or even reverse the condition with some lifestyle changes. Unlimited hay should make up the bulk of the diet, and won't pack on extra calories. No treadmill necessary.
Schimek advises a diet high in fiber and cutting out sugar and high-carbohydrate "junk food" treats completely. Sorry, carrot lovers. "Free-choice Timothy hay provides appropriate fiber and promotes good gut motility. All sugary treats like fruit, carrots, and juices should be completely eliminated to maintain good gut flora and prevent obesity and major metabolic fluctuations." Offering fresh veggies throughout the day can replace expected treats, boost hydration, and encourage normal grazing behavior. "Allowing the rabbit to graze throughout the day will also encourage stability in glucose levels, so offer several small salads and unlimited access to Timothy hay," Schimek says.
There are so few case studies of diabetic rabbits, that it is difficult to predict whether they can enjoy a normal lifespan or whether ongoing health problems should be expected. According to Schimek, the best plan of action is simply to closely monitor your diabetic rabbit. "This would allow for quick intervention with your exotic vet if complications were to arise. If you suspect any changes in your rabbit’s health, it is important to have them evaluated by your veterinarian as soon as possible."
References:
https://www.vetstream.com/pennardvets/html/Factsheets/Otherpets/24_295056.asp
http://www.medirabbit.com/EN/GI_diseases/Metabolic_diseases/Diabetes_en.htm