Do insulin injections make you fat?

INTRODUCTION

A locum now, I work in other people’s surgeries. It can be most instructive. At one surgery I found that a very dedicated partner with a special interest in diabetes was bringing a middle-aged man with type 2 diabetes back for monthly visits. Each time his sugars were high and each time she increased his insulin. Anybody who has run a diabetes clinic will be familiar with this scenario. Increasing the insulin fails to bring down the blood sugar; it simply makes an already tubby middle-aged man fatter and fatter. But why, it crossed my mind, does insulin make people fat?

We are all on insulin, whether endogenous or, as in this patient’s case, injected. So the question is: ‘How does insulin injected peripherally and subcutaneously differ from insulin released in …