After 40, peripheral insulin sensitivity declines in most adults regardless of body weight. The cells of the liver, muscle, and adipose tissue become less responsive to insulin signalling, meaning more insulin is required to achieve the same glucose clearance. This progressive insulin resistance is the upstream driver of type 2 diabetes, but its effects are present and damaging long before a diabetes diagnosis.
What Blood Sugar Instability Actually Feels Like
Adults with poor blood sugar regulation often attribute their symptoms to stress, age, or poor sleep rather than to glycaemic instability. The pattern is recognisable: energy crashes two to three hours after meals, strong carbohydrate cravings, difficulty concentrating in the afternoon, waking between 2 and 4am as cortisol rises to correct overnight hypoglycaemia, and fat storage predominantly around the abdomen. These are not inevitable features of ageing. They are the consequences of a diet that creates repeated blood glucose spikes and crashes.
Dietary Approaches That Stabilise Blood Sugar
- Pair every carbohydrate portion with protein, fat, or fibre to slow gastric emptying and blunt the glucose peak
- Eat vegetables and protein before carbohydrates within the same meal: studies show this reduces post-meal glucose spikes by up to 30 percent
- Replace refined grains with whole grains, legumes, or root vegetables
- Avoid eating carbohydrates alone as snacks: if you eat fruit, eat it with a handful of nuts
- A short walk of 10 minutes after meals significantly reduces post-meal glucose excursions through muscle glucose uptake
- Prioritise sleep: even one night of poor sleep reduces insulin sensitivity the following day by 20 to 30 percent
The Visceral Fat Connection
Repeated blood glucose spikes drive chronic hyperinsulinaemia. Insulin is a fat-storage hormone. When insulin levels are chronically elevated, adipose tissue lipolysis, the breakdown of stored fat for energy, is suppressed. The body cannot access its own fat stores for fuel, so it continually signals hunger for more carbohydrates. This is the biochemical mechanism behind the difficulty of losing abdominal fat on a high-refined-carbohydrate diet.