Excessive glucocorticoids and a high-fat diet can lead to severe high blood sugar and insulin levels in young male rats. The study showed that rats treated with glucocorticoids and fed a high-fat diet had significantly higher blood sugar and insulin levels compared to control rats. These rats also became very resistant to insulin, which is needed to regulate blood sugar. The function of insulin-producing cells in the pancreas was impaired in the treated rats, leading to an imbalance in blood sugar levels. The combination of glucocorticoids and a high-fat diet together worsened insulin resistance and disrupted the body's ability to regulate blood sugar, ultimately causing high blood sugar levels.