Research

Hormonal

Insulin-resistant first-degree relatives of NIDDM patients exhibit a significantly higher percentage of type IIb muscle fibers compared to matched controls, and this morphological trait is a primary determinant of reduced insulin-stimulated glucose disposal.

If you have a family history of Type 2 diabetes, you may naturally have more fast-twitch (Type IIb) muscle fibers, which are less efficient at handling glucose under insulin stimulation. This is not a life sentence; the study links this trait to lower aerobic fitness. Prioritizing aerobic exercise (improving Vo2max) is a key strategy to counteract this specific morphological risk factor for insulin resistance.

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In conclusion, insulin-resistant first-degree relatives of NIDDM patients are characterized by an increased number of type IIb muscle fibers... In a multiple linear regression analysis with Rd as a dependent variable, estimated Vo2max, family history of NIDDM, and number of type IIb fibers (P < 0.001, r2 = 0.64) significantly determined the level of Rd, whereas capillary density did not.
B. Nyholm et al. · Diabetes · 1997

Why this rating

Randomized observation of distinct groups with rigorous metabolic clamping, though observational in design regarding the fiber type origin.

Source

Evidence of an Increased Number of Type IIb Muscle Fibers in Insulin-Resistant First-Degree Relatives of Patients with NIDDM

B. Nyholm et al. · Diabetes · 1997

DOI 10.2337/diab.46.11.1822

cross_sectional · n=46Cited 180×
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DOI resolved against Crossref · corpus check 2026-06-10

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