"Effect of Central Insulin Administration on Whole-body Insulin Sensitivity in Women"
Condition: Insulin Sensitivity
MeSH terms: Insulin Resistance; Hypersensitivity
Study type: Interventional

Summary: 
      The human brain is an insulin sensitive organ. Brain insulin action modulates peripheral
      insulin sensitivity in young lean men. As a underlying mechanism, the investigators
      previously detected suppression of endogenous glucose production and stimulation of glucose
      disappearance to peripheral tissue in response to brain insulin delivery by nasal spray.
      Whether this holds true in young woman is unknown, since differences in brain insulin
      response between sexes have been reported. The investigators will address this question by
      combining the delivery of insulin to the brain as nasal spray with hyperinsulinemic
      euglycemic clamp experiments in natural cycling women.

      In the planned randomized, placebo controlled cross-over study, female participants will
      undergo four hyperinsulinemic euglycemic experiments with tracer dilution, two in the first
      phase and two in the second phase of their menstrual cycle. On one of the study days per
      menstrual phase, subjects will receive intranasal insulin administration, on the other
      placebo spray. The protocol has been successfully applied previously in men. Based on the
      results of this trial, the investigators calculated a required sample size of N=10 for the
      planned study in women.

      These experiments will help to better understand the role of brain insulin action in a
      broader sense. The results can be the basis for larger clinical trials that address the
      sex-specific impact of brain insulin resistance for glucose metabolism and diabetes risk.
    

Detailed description: 
      "Effect of central insulin administration on whole-body insulin sensitivity in women" The
      human brain is an insulin sensitive organ. Brain insulin action modulates peripheral insulin
      sensitivity in young lean men. As a underlying mechanism, the investigators previously
      detected suppression of endogenous glucose production and stimulation of glucose
      disappearance to peripheral tissue in response to brain insulin delivery by nasal spray.
      Whether this holds true in young woman is unknown, since differences in brain insulin
      response between sexes have been reported. The investigators will address this question by
      combining the delivery of insulin to the brain as nasal spray with hyperinsulinemic
      euglycemic clamp experiments in natural cycling women.

      In the planned randomized, placebo controlled cross-over study, female participants will
      undergo four hyperinsulinemic euglycemic experiments with tracer dilution, two in the first
      phase and two in the second phase of their menstrual cycle. On one of the study days per
      menstrual phase, subjects will receive intranasal insulin administration, on the other
      placebo spray. The protocol has been successfully applied previously in men. Based on the
      results of this trial, the investigators calculated a required sample size of N=10 for the
      planned study in women.

      These experiments will help to better understand the role of brain insulin action in a
      broader sense. The results can be the basis for larger clinical trials that address the
      sex-specific impact of brain insulin resistance for glucose metabolism and diabetes risk.
    

Intervention name(s): intranasal insulin; Placebo spray
Intervention type(s): Drug; Drug
Intervention description(s): application of 160 units human insulin; nasal spray containing placebo solution
Intervention MeSH terms: Insulin
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Basic Science