['In mammals, the temperature rhythm is regulated by the circadian pacemaker located in the suprachiasmatic nuclei, and is considered a "marker rhythm". Melatonin, the pineal gland hormone, is a major regulator of the endogenous rhythms including body temperature. Its production is influenced by many factors, such as type 1 diabetes mellitus. In rats, diabetes leads to hypothermia and reduced melatonin synthesis; insulin treatment reestablishes both.', 'To study the body temperature daily rhythm of diabetic animals and the effects of insulin and/or melatonin treatment on its structure.', 'We studied the effects of streptozotocin-induced diabetes (60\xa0mg/kg) on the body temperature rhythm of Wistar rats and the possible modifications resulting from early and late treatments with insulin (6U/day) and/or melatonin (daily 0.5\xa0mg/kg). We monitored the daily body temperature rhythm, its rhythmic parameters (MESOR, amplitude and acrophase), glycemia and body weight for 55\xa0days. Data were classified by groups and expressed as mean\u2009±\u2009SEM. One-way ANOVA analysis was performed followed by Bonferroni posttest. Statistical significance was set at p\u2009<\u20090.05.', 'Diabetes led to complete disruption of the temperature rhythm and hypothermia, which were accentuated over time. All early treatments (insulin or/and melatonin) prevented the temperature rhythm disruption and hypothermia. Insulin plus melatonin restored the body temperature rhythm whereas insulin alone resulted less efficient; melatonin alone did not restore any of the parameters studied; however, when supplemented close to diabetes onset, it maintained the temperature rhythmicity. All these corrective effects of the early treatments were dependent on the continuous maintenance of the treatment.'] Does streptozotocin-induced diabetes disrupt the body temperature daily rhythm in rats?