A study published this week in Nature Communications has identified four subtypes of insulin-producing beta cells (β1-4) in the human pancreas. The study from a team led by stem cell researcher Dr. Markus Grompe (Oregon Stem Cell Center, Portland, OR) challenges the notion of homogeneity among beta cells – the dominant view until now. Initially identified because of their different gene expression profiles for the ST8SIA1 and CD9 genes, each beta cell category is characterized by distinct patterns of basal and glucose-stimulated insulin secretion. Furthermore, individuals with type 2 diabetes (n=8) displayed a significantly different distribution of beta cell subtypes (p=0.028) compared to individuals without the disease (n=17). Specifically, patients with type 2 diabetes presented a higher relative abundance of β3 and β4 cells, subtypes which are typically less responsive to glucose. Notably, people free of type 2 diabetes but affected by obesity (n=7 individuals with a BMI>30 kg/m2) did not differ from healthy individuals in their beta cell composition, lending additional support to the notion that diabetes is specifically related to beta cell dysfunction. We’d be curious to see if these differences in beta cell type distribution are also present in those with type 1 diabetes or prediabetes and if these difference persist throughout the course of type 2 diabetes disease progression. Overall, the discovery of a heterogeneous beta cell population adds greatly to our understanding of pancreatic physiology and information on the distribution of these newly-identified beta cell subtypes could help identify those with early-stage type 2 diabetes or high risk earlier.
-- by Payal Marathe, Abigail Dove, Helen Gao, and Kelly Close