Ketosis-prone diabetes | |
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Other names | KPD |
Specialty | Endocrinology |
Ketosis-prone diabetes (KPD) is an intermediate form of diabetes that has some characteristics of type 1 and some of type 2 diabetes. Type 1 diabetes involves autoimmune destruction of pancreatic beta cells which create insulin. This occurs earlier in a person's life, leading to patients being insulin dependent, and the lack of natural insulin makes patients prone to a condition called diabetic ketoacidosis (DKA). Type 2 diabetes is different in that it is usually caused by insulin resistance in the body in older patients leading to beta cell burnout over time, and is not prone to DKA. KPD is a condition that involves DKA like type 1, but occurs later in life and can regain beta cell function like type 2 diabetes. However, it is distinct from latent autoimmune diabetes of adults (LADA), a form of type 1 sometimes referred to as type 1.5 that does not occur with DKA.[1] There are also distinctions to be made between KPD and LADA as patients who exhibit KPD symptoms can regain beta cell function similar to type 2 diabetics whereas LADA will not exhibit this reclamation of beta cell function.
KPD is readily diagnosable because it presents a single characteristic, ketoacidosis, which confirms it as ketosis-prone diabetes.[2] KPD comes in four forms depending upon the presence or absence of β-cell autoantibodies (A+ or A−) and β-cell functional reserve (β+ or β−).[3] Other styles of classification have been used for KPD, including styles incorporating BMI, but the Aβ system has been found to have the highest accuracy and predictive value of all the systems utilized.[4] The autoantibodies used to diagnose the A+ subtypes of KPD include the autoantibodies detected in patients with type 1 diabetes, including Glutamic Acid Decarboxylase 65 (GAD65), Zinc Transporter T8 (ZnT8), Islet Antigen-2 (IA-2), and HLA class II type 1 diabetes susceptibility alleles.[5]
There is clearly a spectrum of clinical phenotypes among patients with islet autoantibodies who do not present with ketosis, including those termed "latent autoimmune diabetes in adults" (LADA) (30), "type 1.5 diabetes" (31,32,33), and "slowly progressing type 1 diabetes" (34). A similar spectrum exists in KPD that includes the very different phenotypes of A+β− and A+β+ KPD. A+β− KPD is synonymous with classic, early onset autoimmune type 1 diabetes; A+β+ KPD may overlap with LADA. However, there are differences between LADA, as recently defined by the Immunology of Diabetes Society, and A+β+ KPD patients; most importantly, the definition of LADA excludes patients who require insulin within the first 6 months after diagnosis, whereas the majority (90%) of A+β+ KPD patients present with DKA as the first manifestation of diabetes and therefore require insulin at the start.