Design: Prospective cohort follow-up (HAPO Follow-Up Study)
Population: 4,693 women, 10–14 years after delivery
Primary outcome: Prediabetes or diabetes
Effect: Adjusted risk ratios 2.14–2.88 for insulin-deficient, insulin-resistant and mixed GDM vs no GDM

Using the prospective Hyperglycemia and Adverse Pregnancy Outcome Follow-Up Study, researchers classified gestational diabetes by physiology as insulin-deficient (3.0% of 4,693 women), insulin-resistant (9.0%), mixed-defect (1.6%) or unclassified (0.7%), and looked at outcomes 10–14 years after delivery. The paper appeared in Diabetes Care on 1 October.

Compared with women without GDM, the insulin-deficient, insulin-resistant and mixed subtypes were each associated with higher risk of prediabetes or diabetes, with adjusted risk ratios of 2.14–2.88, and with metabolic syndrome and higher predicted cardiovascular risk. Only the insulin-resistant subtype was associated with dyslipidaemia.

The practical reading is that subtype does not identify a low-risk group. Whatever the mechanism behind a woman's GDM, she needs long-term follow-up.

Every woman with a history of GDM needs periodic glucose testing after delivery, whatever the subtype.
Check blood pressure, lipids and waist at postpartum and later reviews, not glucose alone.
Women with insulin-resistant GDM showed an added dyslipidaemia signal; a lipid profile is reasonable at follow-up.
Record a GDM history in the problem list so it is visible years later in general practice.

Why it matters

It removes the idea that a 'mild' or insulin-deficient GDM pattern can be followed less closely.

The statistics, in plain English

Adjusted risk ratios of 2.14 to 2.88 mean roughly two to three times the risk of later dysglycaemia compared with women without GDM, after accounting for measured differences. Small subtypes such as unclassified (0.7%) have too few women for a firm conclusion.