Expression of IL-1β by human β cells exposed to a diabetic milieu. Double immunostaining for IL-1β appears in red (b and d) and insulin in green (a and c) in human islets cultured on extracellular matrix–coated dishes and exposed for 4 days to media containing 5.5 mM glucose (a and b) or 33.3 mM glucose (c and d). Double immunostaining for IL-1β in red (f and h) and insulin in green (e and g) in tissue sections of pancreata from a nondiabetic patient (e and f) and from a patient with type 2 diabetes (g and h). In situ hybridization for IL-1β mRNA in red (j, l, and n) double immunostained for insulin in green (i, k, and m) in tissue sections of pancreata from a patient with type 2 diabetes (k, l, m, and n) with anti-sense probe (l) and with sense probe (negative control) (n), and from a nondiabetic patient (i and j) using anti-sense probe (j). Immunostaining for IL-1β in LPS-treated macrophages (positive control) (o). Magnification: ×250.