Multicentric, observational, cross-sectional study in Italy. The aims are to evaluate the basal/total ratio of daily insulin dose (b/T) in diabetic outpatients type 1 (T1) and type 2 (T2) on basal-bolus regimen, by investigating whether there is a relationship with HbA1c and episodes of hypoglycemia.

The study was commissioned by the Italian Association of Clinical Endocrinologists (Associazione Medici Endocrinologi - AME) and approved by the Ethical Committee of Cuneo Hospital (BASAL Study- OSS 001/2016 - rif ENDO 30). The research was open to all specialists taking care of patients with diabetes in Italy.

The primary endpoint was glycemic control, evaluated by HbA1c levels, according to b/T.

Secondary endpoints were occurrence of major hypoglycemic episodes according to b/T; differences between patients with T1 and T2.

An ad hoc form was developed and used to record all medical findings. The form was emailed to all participating centers who then emailed or faxed it back to our data manager. Data were checked for accuracy.

The following data were required: age, gender, body weight and height, country of origin, type of diabetes and its duration, units of basal and total (basal plus prandial) daily insulin, type of basal insulin (Glargine, Detemir or Degludec), use and dosage of metformin, and number of major hypoglycemic episodes (<40 mg/dL or requiring caregivers intervention) in the last three months. Serum creatinine and HbA1c levels obtained within the previous two months were also required.

Each participating center recruited between 20 and 40 diabetic outpatients. Inclusion criteria were as follows: adult outpatients (≥20 and ≤80 years) with T1 or T2 diabetes mellitus, on basal-bolus insulin regimen (basal insulin, i.e. Glargine, Detemir or Degludec, plus at least two prandial insulin shots) for at least six months, usually assuming three daily meals, and capable of informed consent.

Inclusion Criteria:

• adult outpatients (≥20 and ≤80 years);
• T1 or T2 diabetes mellitus;
• basal-bolus insulin regimen (basal insulin, i.e. Glargine, Detemir or Degludec, plus at least two prandial insulin shots) for at least six months;
• assuming three daily meals;
• capable of informed consent.

Exclusion Criteria:

• pregnancy;
• breast-feeding;
• severe liver or renal failure (eGFR <30 mL/min/1.73 m2);
• use of OADs (except for metformin);
• hospitalization for any cause in the last six month;
• glucocorticoid treatment in the last six month;
• oncologic treatment in the last six month;
• Ramadan in the last six months.

All diabetic patients respecting eligibility criteria