For the administration of insulin, different needles are available with a length from 5 to 12.7mm. Insulin injections with a needle of 8 mm is injected in a lifted skinfold, a 5 mm needle can by used without lifting a skinfold (1). In the Netherlands obese people (BMI ≥ 30) are usually advised to use an 8mm or even longer needle (1). Increased BMI and the thickness of the subcutaneous tissue slow insulin absorption (2, 3, 4), possibly related to reduced subcutaneous blood flow. Furthermore, the capillaries are located just under the skin and between the fat and muscle layer. This could possibly determine the absorbing speed (2). It is not know if the administration of insulin with a 5mm needle by obese people has a different influence on the HbA1c compared to longer needles. The hypothesis of this study is that for the purpose of insulin injections, a 5 mm needle can be used without negative effects on metabolic parameters in patients with Diabetes Mellitus (DM) and a Body Mass Index (BMI) ≥ 30.

Inclusion Criteria:

• Male and female adult patients diagnosed with type 1 and type 2 diabetes mellitus, treated with insulin injections for at least one year and:

  • using an insulin pen
  • a BMI > 30 kg/m2
  • a skinfold thickness of >10 mm at the injection sites
  • stable glycaemic control, with HbA1c between 6 and 10%
  • capable of reading the written information
  • prepared to, and capable of signing an informed consent

Exclusion Criteria:

• Patients who:

  • change their own insulin dosage and are not prepared to keep a record of these changes
  • have hypoglycaemia unawareness
  • are pregnant or wish to become pregnant
  • have a BMI < 30 kg/m2
  • have a skinfold thickness <10mm
  • have skin problems including lipodystrophy