Diabetes mellitus (DM) is a metabolic disease caused by the absence or dysfunction of insulin; a hormone secreted by the pancreatic beta cell (β-cell) whenever blood glucose exceeds the normal physiological value. The longterm effects of the disease on the body's organs are one of the leading causes of death in the world. To alleviate this global burden of DM, a number of studies have been conducted to lower blood glucose levels in patients. For genetic and ethical reasons, humans are far from being appropriate subjects in such investigations and the use of animal models has therefore been the way forward. Streptozotocin (STZ) is a glucosamine-nitrosourea compound that selectively destroys β-cells and has been widely used to induce Type I diabetes in several animal species. Recent literature has shown that a non-diabetic dose of STZ, combined with a high-fat diet (HFD), can mimic Type II diabetes. Yet, researchers seldom provide data to corroborate the high sensitivity of STZ on these animal models. In addition, there are few reports of potentially fatal effects of the use of STZ as a supplement in obese HFD animals when attempting to induce Type II diabetes. The present review article highlights the parameters that could be at the origin of the extreme sensitivity and vulnerability of obese animals to STZ.