The goal of this clinical trial is to examine the effect of 3 versus 6 daily meals of isocaloric diets on glycemic control and variability in individuals with type 1 diabetes. Participants will be randomized in a crossover clinical trial and will receive two different types of isocaloric diet interventions, in 3 meals/day (calorie distribution: 30% at breakfast, 40% at lunch and 30% at dinner) or 6 meals/day (calorie distribution: 20% at breakfast, 10% at morning snack, 30% at lunch, 10% at afternoon snack, 25% at dinner and 5% at evening snack), for three weeks, with a 4-week washout period between diets.

This is a single center, randomized, open-label, non-inferiority and crossover clinical trial. Subjects with type 1 diabetes (T1D) and will be recruited through advertisement on the web page of Hospital de Clínicas de Porto Alegre (HCPA), type 1 diabetes outpatient clinic of HCPA, local newspaper, television and social media, or referred by a doctor or nutritionist, from external to HCPA services. After screening and selection according to inclusion criteria, participants will undergo a clinical, laboratory and nutritional evaluation following a standard assessment protocol. After all baseline assessments, they will be randomly allocated to one of the following interventions for 3 weeks and after a washout period, they will be in the other intervention. While glycemic control (A1c and Glycated albumin) and variability (6 points daily capillary blood glucose tests) are assessed during the baseline period, the first week of each intervention, and the last week of washout and continuous interstitial glucose measurements that are performed in the last 14 days of each intervention. Blinding is maintained outcome assesment.

Inclusion Criteria:

• • Adults (18 to 60 years old) with a medical diagnosis of type 1 diabetes mellitus

  • Individuals who perform carbohydrate counting
  • Individuals diagnosed > 12 months ago
  • Perform daily glycemic control using a blood glucose monitor or use of a glucose sensor
  • Have the ability to understand and be able to adhere to the proposed interventions.
  • Complete a detailed 3-day food record for one week prior to the intervention and record episodes of hypoglycemia (<70 mg/dL) and hyperglycemia (>180 mg/dL)
  • Able and willing to provide written informed consent and comply with the requirements of the study protocol.

Exclusion Criteria:

• Individuals with glycated hemoglobin ≥ 11%
• Individuals who are using NPH insulin
• Retinopathy with vision deficit that limits the activities proposed in the disciplines.
• Individuals with gastrointestinal disease such as celiac disease, Crohn's disease and Irritable Bowel Syndrome (IBS)
• History of bariatric surgery
• That you are following a carbohydrate, protein and/or fat restriction diet
• Individuals with BMI ≥ 40kg/m2
• Chronic kidney disease with estimated glomerular filtration <30mL/min per 1.73 m2.
• Liver failure or chronic viral hepatitis
• Active or progressive neurodegenerative disease
• Use of medications that affect glucose metabolism (corticosteroids and immunosuppressants) or cause weight loss. ● Treatment with weight-reducing agents (e.g., orlistat, sibutramine, topiramate, liraglutide) in the last 12 weeks prior to screening.
• Treatment with thyroid hormone that has not been maintained at a stable dose in the last 12 weeks prior to screening.
• History of active substance abuse (including alcohol) in the last year.
• Serious psychiatric illness: Mood disorders, anxiety disorders, severe psychotic disorders, and personality disorders that are revealed or identified in the clinical evaluation, listed or reported in the medical record, and that have no clinical findings.
• Predisposition to or diagnosis of eating disorders.
• Women who are pregnant, intending to become pregnant during the study period, or who are breastfeeding.
• Hyperglycemia characterized by acute symptoms: polyuria, polydipsia, and/or weight loss in the last 3 months. ● Metabolic and acute complications of diabetes such as ketoacidosis or hyperosmolar coma.
• Night workers who work after 10 pm.

The participants and the care providers will not be blinded. People involved in assessing outcomes and with data analysis will be blinded.