Diabetes mellitus can be frustrating to treat in veterinary practice, but newer nutraceutical products may offer some aid in stabilizing difficult patients.
Regulators of glucose absorption
Dietary therapy has been a mainstay of diabetes treatment. Dietary fiber is known to reduce glucose absorption from the gut through a number of mechanisms, increasing glycemic control.
Some emerging thought speculates that insulin resistance may develop (in part) from high carbohydrate dry diets fed overweight patients. Cats (obligate carnivores) and dogs (facultative carnivores) may, in fact, have innate insulin resistance mechanisms, making them less tolerant of the highly digestible carbohydrate diets recommended in principle for humans, and provided by typical dry weight loss diets. It is well to remember that cats have no requirement for carbohydrates at all, and that insulin resistance may have developed in this species as a mechanism for coping with exogenous glucose shortages. Are we hastening progression of the disease by feeding diabetic cats high carbohydrate dry weight loss diets?
To this end, some are feeding high quality maintenance, prescription or homemade diets with quality meat protein and lower digestible carbohydrate levels, adding soluble fibers (psyllium hulls, apple pectin or guar gum) to take advantage of fiber effects on glycemic control. This is particularly important where a pet may be a picky eater or has nutritional needs not covered by commercial high fiber, weight loss diets (i.e. food allergies, renal failure, etc).
Regulators of insulin availability or release
Gymnema sylvestre is an herb used in Ayurvedic medicine, a 2000 year old cultural system from India. Gymnema was used in the treatment of diabetes, and recent clinical and experimental studies suggest this use was warranted.
Numerous case series reports indicate that gymnema improves glucose tolerance and clinical status in human diabetics. In streptozocin treated rats, administration of gymnema extract was observed to increase serum insulin levels as well as the absolute number of pancreatic islet cells. The same group showed that gymnema improved glucose uptake in target tissues.
While the mechanism by which gymnema acts has not been established, it may be useful in regulating difficult veterinary diabetic patients. Clinical use has suggested that gymnema must be adminisitered for 2-3 months before the effects are evident. It is available alone, but more often in combination with other herbs traditionally used for treatment of diabetes, including momordica charantiaca (bitter melon), fenugreek, ginseng, and cloves.
Glandular therapy is another alternative occasionally recommended. Glandulars are extracts of specific organs or glands, given to support function of that organ. Pancreatic glandulars contain freeze-dried pancreatic tissue, as well as small amounts of pancreatic enzymes.
Research from Harvard has investigated the use of oral tolerization in the treatment of autoimmune disease, including diabetes in humans. Since 40-50% of dogs have autoantibodies to islet cell antigens, administration of pancreatic glandular may be a rational approach, despite the fact that doses and efficacy have not been examined. Clearly glandular therapy, if effective, is best used early in the disease to decrease destruction of pancreatic beta cells.
Regulators of insulin receptor and post-receptor effects
Chromium has long been recommended for treatment of diabetes, and more recently, research from Deborah Greco at Colorado State lends support to use of vanadium in dogs and cats. Vanadium appears to have insulin-like effects in people and experimental animals. In Type I diabetes, vanadium appears to reduce insulin requirement, and Type II diabetes, vanadium appears to increase secretion of insulin, possibly by reversing glucose toxicity, as well as exerting insulin like effects at target tissues. The mechanism by which vanadium works is unknown, but appears to be a post-receptor effect.
Chromium is thought to increase receptor number, receptor sensitivity and receptor phosphorylaton. Current research by the Iams Company suggests that chromium is effective at improving glucose tolerance in dogs. In a new study on nondiabetic obese and nonobese cats, chromium supplemented at 100mcg daily did not effect glucose tolerance. This study agrees with earlier studies indicating that chromium supplementation changes chromium levels and metabolism diabetic, but not normal people.
Consequences of uncontrolled diabetes
There is little doubt that diabetes imposes oxidative stress on many tissues and organs. Antioxidant supplementation for human diabetic patients has strong support from the medical literature.
Vitamins C and E are two of the most widely studied antioxidants. These micronutrients are employed in nutraceutical doses to ameliorate oxidative stress and potentially reduce related symptoms such as diabetic cataracts and diabetic nephropathy (in people). Antioxidant supplementation for diabetic veterinary patients should be strongly considered and is safe for long term use.
Marine fish oil, a source of omega 3 fatty acids, may increase insulin sensitivity. It is better studied, however, as a treatment for diabetic neuropathy. Possible mechanisms by which fish oil exerts these effects may be changes in cell membrane composition or transmembrane ion transport.
Alpha-lipoic acid has been shown to improve diabetic neuropathy in people. It also used in slowing the progression of cataracts in people. Alpha-lipoic acid may be useful for both of these reasons in diabetic dogs and cats.
Clinical indications for use of nutraceuticals
Some of the nutraceuticals described above may aid in regulation of glucose levels in difficult diabetics, and there are others being investigated which may be useful, including niacin, arginine, magnesium and certain herbs. They have the potential for reducing insulin requirements and providing more even glycemic control. An argument can be made for using most of these supplements early in the disease, in hopes of slowing beta-cell destruction and amyloid deposition.
In my practice, vanadium, fish oil and antioxidants are recommended for most diabetic patients. For those pet owners willing and able to give a larger number of oral medications, other nutraceuticals, herbs and and chinese herbal combinations may be helpful. It is important to inform clients that these supplements are experimental and cannot be relied upon to maintain control of this disease in the absence of insulin therapy.
Table 1: Nutraceutical Doses and Warnings
|Compound||Dose||Adverse or overdose effects|
|Metamucil||proportional to human voluminous or loose stool, gas – on label||constipation|
|Apple Pectin||proportional to human voluminous or loose stool, gas, on label||constipation|
|Guar gum||proportional to human voluminous or loose stool, gas, on label||constipation|
|Vanadium||0.2 mg/kg/day||anorexia, vomiting, possible renal toxicity?|
|Vanadyl sulfate||1 mg/kg/day||anorexia, vomiting, possible renal toxicity?|
|Chromium||50-300 mcg/day||anorexia, vomiting, possible renal toxicity?|
|Fish oil||100mg/kg divided daily||nausea|
|alpha-lipoic acid – Dogs||Dogs: no more 80 mg/day||anorexia, disorientation, seizures at hight doses|
|alpha-lipoic acid – cats||Cats: no more 25 mg/day||anorexia, disorientation, seizures at hight doses|
|Vitamin C||50mg/kg, up to 1000mg||daily in large dogs|
- Anderson RA, 1998 . Chromium, glucose intolerance and diabetes. J Am Coll Nutr 17(6):548-55
- Cohn LA, Dodam JR, McCaw DL and DJ Tate, 1999. Effects of chromium supplementation on glucose tolerance in obese and nonobese cats. AJVR 60(11): 1360-1363.
- Cunningham JJ, 1998. Micronutrients as nutriceutical interventions in diabetes mellitus. J Am Coll Nutr 17(1):7-10
- Gerbi A; Maixent JM; Ansaldi JL; Pierlovisi M; Coste T; Pelissier JF; Vague P; Raccah D, 1999. Fish oil supplementation prevents diabetes-induced nerve conduction velocity and neuroanatomical changes in rats. J Nutr 129(1):207-13
- Greco DS, 1999. Treatment of Non-Insulin-Dependant Diabetes Mellitus in Cats Using Oral Hypoglycemic Agents. Current Veterinary Therapy XIII. W.B. Saunders, Philadephia, PA, p.350.
- Huang YJ; Fang VS; Juan CC; Chou YC; Kwok CF; Ho LT, 1997. Amelioration of insulin resistance and hypertension in a fructose-fed rat model with fish oil supplementation. Metabolism 46(11):1252-8
- Reinhart GA, Carey DP, 1998. Recent Advances in Canine and Feline Nutrition, Volume II. Orange Frazier Press, Wilmington, OH.
- Shanmugasundaram ER; Gopinath KL; Radha Shanmugasundaram K; Rajendran VM, 1990. Possible regeneration of the islets of Langerhans in streptozotocin- induced diabetic rats given Gymnema sylvestre leaf extracts. J Ethnopharmacol 30(3):265-79
- Shanmugasundaram KR; Panneerselvam C; Samudram P; Shanmugasundaram ER, 1983. Enzyme changes and glucose utilisation in diabetic rabbits: the effect of Gymnema sylvestre, R.Br. J Ethnopharmacol 7(2):205-34
- Stiefel P; Ruiz-Gutierrez V; Gajon E; Acosta D; Garcia-Donas MA; Madrazo J; Villar J; Carneado J, 1999 . Sodium transport kinetics, cell membrane lipid composition, neural conduction and metabolic control in type 1 diabetic patients. Changes after a low-dose n-3 fatty acid dietary intervention. Ann Nutr Metab 43(2):113-20