Loss of insulin production can be partial or complete. This differentiates between Type I diabetes and Type II diabetes. Damage to the pancreas or beta cells, specifically, can result in lost insulin production. Damage to beta cells is usually permanent. No other system can produce insulin or perform their duty, so once enough beta cells are lost to cause insulin deficiency, diabetes signs will become apparent. This condition is known as Type I diabetes, or insulin-dependent diabetes. These individuals will generally have a lifelong need for insulin administration and may suffer the worst consequences of diabetes. In cats, 60 to 80 percent of diabetics fall into this category.
Development of Type II, or noninsulin-dependent diabetes, is closely associated with obesity. Twenty to 40 percent of feline diabetics fall into this category. In this type of diabetes, insulin production and release may be impaired or delayed. More importantly, sensitivity and number of insulin receptors is diminished, so insulin may be present but unable to do its job.